So I dropped the ball on that Wikipedia App comparison. Two things happened simultaneously which lead me to just forget the whole idea. First, I realized every single Wiki App out there sucks. They're all slow, quirky, or shallow. Second, visiting Wikipedia results from a Google search in mobile Safari started automatically pushing me to the mobile Wikipedia site. Perfect! The mobile Wiki site is fast, familiar, and easy to navigate. I really don't see why you'd bother with a seperate app, especially since many of them cost money!
Among other changes around here, we're going to be hearing from a friend and former colleague of mine, Pete Buletza. Pete is developing iPhone apps now, and spends a ton of time annoying me with iPhone app recommendations. I assure you he knows what he's talking about. In fact, a few of the comments on here have been by him (NullPtr). So there's that. I'm not sure what his timeframe is exactly but you should be seeing a post from him here within the next few days.
Now that the clerical stuff is out of the way, I'd like to tell you how to spend the last $5 in your wallet. Civilization: Revolution is simply the best iPhone port of a full game I've ever seen. I've been playing it for a few days now, and most of the time I honestly can't tell the difference between Civ on the iPhone and on my Xbox 360. Despite long initial load times, the game plays quickly and smoothly. It's easy to just pull it out of your pocket, play a few turns, and go on about your day. Once I've spent a little more time with it, I'll write up a full review with screenshots and all. But trust me, just go ahead and buy it now, and find out for yourself.