fast to take notes, try snapping pictures of each slide instead. try to sit off to the side so that you’re not too distracting, and don’t use a flash.
receipts: if you go out to eat in a group and the restaurant will not give you individual receipts, just take a photo of the group receipt for your records. for that matter, you can take a photo of all your receipts for your own records before you submit them.
name badges: if you meet someone you want to remember and they don’t have a business card, photograph their name badge instead. i usually take a photo of my own name badge too, 