I use ColorNote for note-taking; not sure if you mean more extensive, like, in-class note-taking or just jotting down things to remember, but since the virtual keyboard on my Thunderbolt would be extremely annoying to take notes on (not to mention autocorrect)... I use ColorNote to take down things like grocery lists and write down birthdays and such.
I use Trillian mobile for my IMs.
I have been trying out an app called "Schedule Planner" for my calendar. I'm not sure yet how I feel about it. It's all right, I guess - I would like a calendar that I don't have to spend hours every Sunday programming, but I have yet to come across one that reads my mind.
I use spreadsheets off the Google Drive app. Love that one.
'Scuse me, gents, but -
I use PTracker instead of MyDays - I really like it because it has a list of symptoms you can load into the calendar, too. Helps me to look over stuff like "Oh, it looks like I always get a headache three days before the start of my visit from Aunt Flo. Guess I can plan for that next month."
Another vote for Pandora. I couldn't get by with only five stations, though... I have my rock station, my blues station, my jazz station, my techno station, plus a bazillion stations seeded off of artists I like. I do have French music on there, but I doubt they're indie artists or anything. >.>;
I love trying new apps and reading about what works for people. I'm so glad this thread got started!