Basically just looking for all SmartPhone users to post their top 5 favourite apps, you don't need to give a reason for them or anything like that, but that'd also be helpful.. Just state the phone you're using and build your list .
My top 5 iPhone apps are:
1) Traffic Rush (59p) - Super super addictive!
2) Light (Free) - Lets me use the LED flash from the camera as a torch, especially useful in the winter months.
3) Facebook (Free) - Supports "Push" and Facebook Chat, and works extremely well, definitely better than just using Safari.
4) BBC News (Free) - An easy way to keep track of the news.
5) Megajump (Free) - Another highly addictive game, and it's free.
Mainly steered away from paid for apps, unless I've actually tried it one someone else's phone, so I'll look forward to everyone elses recommendations.