New toy

So I have finally leaped into the new millennium by buying a smartphone. It's an Android -- a Samsung Galaxy S II. I got it through Credo, which is a company that donates some of its profits to progressive causes. (Denys and I have had a long distance service from them for many years, going back to when they were called Working Assets.) They don't have their own network and are a reseller of Sprint's service.

I've long wanted a mobile internet connection, and we'll see if it's worth the cost. I only activated it yesterday, so I've still got a lot to learn. I'm interested in app suggestions from folks who use Androids. I'm also interested in hints and advice for a newbie. How do you use your smartphone? How do I get the best bang for the buck? (For example, how often do you use wifi rather than the phone network?)

Honestly, I'm so new at this that I don't even know what questions to ask yet.