Endomondo !!!!
Free your endorphins : )
I love this app!!!
I have used it to track over 1,000 miles of cycling this year.
The android app is just a small part of the entire service.
With endomondo you get challenges with your friends live updating of your route global challenges personal bests summary teams more With their great android app
you get the ability to track duration with option of auto pause distance speed avg.
speed calories heart rate average heart rate listen/control music view current position and track on map view previous workouts set goal and get mile by mile updates on progress
I personally really enjoy being able to use my bluetooth heart rate monitor with this android app. http://www.zephyr-technology.com/9600.0112.html
All my workout info is then updated live to the endomondo website where I can later inspect my workout in detail.
If you are looking for a service/app to track your rides/workouts you have got to give this one a go.
bicycles.stackexchange.com/users/615/Mike Grace
My Tracks is an app by Google that will record a path you rode with stats.
You can upload your path to Google Maps and stats to Google Docs, or create a gpx/kml file for uploading to other biking, running, or fitness / mapping apps.
bicycles.stackexchange.com/users/213/Gary.Ray
A few folks I work with use Strava ( http://www.strava.com ).
There are android and iphone apps, and you can also upload files from Garmin devices.
Aside from the standard gps, route tracking stuff, the web site has a social focus.
You can follow other riders if you wish.
The site also allows you to define road segments and will show leaderboards, king of the mountain badges, and personal bests.
bicycles.stackexchange.com/users/2446/Andrew Forbes
I've used Sports Tracker a lot on Symbian phones and they now have an Android version coming out (as well as an iPhone version).
It can beep on auto-laps for example every kilometre.
You can review your workouts on the phone, something I don't think Endomondo can do.
You can use it with a Bluetooth Polar heart rate monitor.
You can see things like this on both the phone and website: route plotted on a scrollable, zoomable map with lap markers (using Open Street Map), duration, distance, average and max speed, energy use, charts of altitude vs. distance, heart rate distribution (light, moderate, hard), heart rate vs. time, speed vs. time and lap timings.
You can upload to their site (which is a bit Flash heavy for my liking) with various permissions (private, visible to friends, visible to everyone), Twitter, Facebook.
Also if you take photos during the workout, it can upload those to the site too, and shows them on the map.
You can also edit and export workout routes, and replay them.
bicycles.stackexchange.com/users/1593/Hugo
CardioTrainer is an app that also works with the GPS functionality to track your workouts, and can create tracks and virtual training partners if you do the same routes.
bicycles.stackexchange.com/users/213/Gary.Ray
I use RunKeeper Pro ; from January it's free for Android; here is the description in Android Market.
It's not only for cycling, but you can choose the activity type to be tracked by GPS, define custom routes and use audio coaching to know your distance, speed, time; then you can see online, in your personal account, a detailed report and a map with your path; if you want, you can also share those details with friends, and create or attend races.
You can also monitor your heart rate, if using along with
Polar WearLink®+ transmitter with Bluetooth
® for the Android,
but I didn't try it.
bicycles.stackexchange.com/users/1231/Adinia
SportsTrackLive is another app listed as supporting the Zephyr heart rate monitor.
I haven't tried it; anyone who has, feel free to comment or edit this answer with more information.
bicycles.stackexchange.com/users/454/Brian Campbell
iMapMyRide is great.
It records and uploads all your route data to the iMapMyRide web site.
Once uploaded you can view the route on a Google map, see the total distance travelled, see a chart of the elevation plus the total gain, add notes, log the workout and share the route with others.
I really can't recommend it enough
bicycles.stackexchange.com/users/446/Phil Hale
My app IpBike Is designed for a phone mouted on the bike, the emphesis on giving you all the information in a clear and consistant way on one basic screen while riding.
Has full support for ANT+ sensors HR, speed, Cadence Speed and Cadance and Power sensors on compatible phones.
Pressure based altitude of compatible phones.
Direct upload for Stava, Runkeeper and Attackpoint.
Can export rides as .gpx, .tcx, .csv, .fit
bicycles.stackexchange.com/users/3723/Ifor
VeloComputer appears to be an attempt at turning a phone into a complete cycling computer.
Version 7, which is available for Android, uses GPS for measuring position and speed, and the accelerometer to measure cadence.
They also sell Bluetooth enabled wheel and pedal sensors, for more accurate speed and cadence, though those seem to only be supported on Blackberry at the moment.
I have not tried this; it looks interesting, though some of the reviews indicate that it's a bit flaky.
Does anyone else have experience with it?
bicycles.stackexchange.com/users/454/Brian Campbell
Run.
GPS is mentioned in the list of apps supporting the Zephyr heart rate monitor.
I haven't tried it; anyone who has, feel free to comment or edit this answer with more information.
bicycles.stackexchange.com/users/454/Brian Campbell
Not the most convenient way of measuring your heart rate while cycling, but Instant Heart Rate is a neat program which might be useful when you to take a break.
You use your phone's camera and LED flash (if it has one, otherwise any bright light source) to measure your heart rate by pressing the camera and flash against your finger, and it detects fluctuations in the oxygen content of your blood by detecting changes in color.
bicycles.stackexchange.com/users/454/Brian Campbell
Try this free app for measuring your heart rate: Sports Heart Rate Monitorsee: https://play.google.com/store/apps/details?id=com.js.hr you do not need any external hardware and it measures your heart rate quickly.
You just need to press it softly against your chest and it will readout your beats per minute.
bicycles.stackexchange.com/users/3652/nokia
You didn't say what you want your app to do.
However, I use OruxMaps for navigating and tracking.
I like it because you can create a local copy of online maps to use where 3G internet connection is not available
bicycles.stackexchange.com/users/3666/Eran Ben-Natan
I have an Android smartphone, with GPS, accelerometer, 3G internet connection, and other features that seem useful for bicycling. Are there any good bicycling apps on Android?  One app per answer please; feel free to answer multiple times.
Bicycling apps for Android
bicycles.stackexchange.com
<bike-computer><software><android>
bicycles.stackexchange.com/questions/1689
bicycles.stackexchange.com/users/454/Brian Campbell
Endomondo, My Tracks by Google, CardioTrainer, RunKeeperPro, SportsTrackLive, iMapMyRide, IpBike and Velocomputer are just some of the Apps available for Android. Sports Tracker on Symbian is now bringing out an Android and iPhone version. There is a number of available bicycling apps for Android, which involve navigating and tracking, documenting your health statistics, managing your training and finding virtual training partners. These include Endomondo, Strava, My Tracks, Sports Tracker, CardioTrainer, RunKeeper Pro, SportsTrackLive, iMapMyRide, IpBike, VeloComputer, Zephyr heart rate monitor, Instant Heart Rate, Sports Heart Rate Monitorsee and OruxMaps.
There is a number of available bicycling apps for Android, which involve navigating and tracking, documenting your health statistics, managing your training and finding virtual training partners. These include Endomondo, Strava, My Tracks, Sports Tracker, CardioTrainer, RunKeeper Pro, SportsTrackLive, iMapMyRide, IpBike, VeloComputer, Zephyr heart rate monitor, Instant Heart Rate, Sports Heart Rate Monitorsee and OruxMaps.