user78: I have not already started to try but I'm a good webmaster and I'm just asking which way is more suitable for sending and keeping data from sensors and I/0 state in a database.
Here are some points:

Post versus get
MySQL or others types
Security layers
Graphics render of data's (google API?)
PHP, ruby, JavaScript...
Able to send data request's to Arduino's
Ethernet shield, wifi, I2c ???
Access via Android app...

Anyway, the goal here is to know pros and cons of integrate all my Arduino through database.

user82: It depends on your skills and what you have in your Arduino "box".
Let's assume you have an ethernet or WiFi shield.
I would go with a PHP script (I'm a PHP dev, but any language will fit) that accepts POST requests sent by the board and store them in a SQLite db.
Why SQLite instead of MySQL? Well, it's just a matter of data portability. You copy the SQLite file or send it via email and you're done: there are plenty of clients out there to read your db, in *nix based machines is frequently integrated in the OS. 
MySQL requires a sort of "infrastructure" to be written/read.

78: <p>I have not already started to try but I'm a good webmaster and I'm just asking which way is more suitable for sending and keeping data from sensors and I/0 state in a database.</p>

<p>Here are some points:</p>

<ul>
<li>Post versus get</li>
<li>MySQL or others types</li>
<li>Security layers</li>
<li>Graphics render of data's (google API?)</li>
<li>PHP, ruby, JavaScript...</li>
<li>Able to send data request's to Arduino's</li>
<li>Ethernet shield, wifi, I2c ???</li>
<li>Access via Android app...</li>
</ul>

<p>Anyway, the goal here is to know pros and cons of integrate all my Arduino through database.</p>
 82: <p>It depends on your skills and what you have in your Arduino "box".
Let's assume you have an ethernet or WiFi shield.</p>

<p>I would go with a PHP script (I'm a PHP dev, but any language will fit) that accepts POST requests sent by the board and store them in a SQLite db.</p>

<p><strong>Why SQLite instead of MySQL?</strong> Well, it's just a matter of data portability. You copy the SQLite file or send it via email and you're done: there are plenty of clients out there to read your db, in *nix based machines is frequently integrated in the OS. </p>

<p>MySQL requires a sort of "infrastructure" to be written/read.</p>
