Your must-have apps are not my must-have apps because we have different jobs and different requirements. For example, I don't use Facebook or Twitter, so any app that involves those is useless to me. I have a bubble-level app on my Droid, which would probably just get in your way.
That said, there are some good ideas in your post, and good ideas from other users. Keep the ideas flowing. Some will be good, some mediocre, and some downright lame, but don't reject anything until you've looked it over.
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