I download lots of iOS apps, mainly out of curiosity. Some I grow to use others just disappear. One which I use more and more and has got better and better is Evernote. With the tagline “Remember Everything” you use Evernote via the web, iOS, Android, BlackBerry etc. You can do simple notes, todo lists, upload files or images. I started to use it for making notes at conferences. The Evernote ecosystem has grown and a great feature is the web clipper. This add-in for your favorite browser clips all or part of a web site and saves it as an evernote note. Once in evernote it is easy to search through it via tags; my google searches even checks my evernote account now (with permission). Skitch is a recent acquisition but makes annotating images dead easy on your desktop, iPad or Android device (and then saves the results to Evernote).
It works on a freemium model. You get everything with some restrictions (60MB upload a month, no offline data on mobile devices). They get you hooked then you can pay for unlimited access, which I’m giving serious consideration to. Why not give it a try at your next conference? I hear CUP XIII should be good fun.