Atomic Web Browser - Ok, sure, it looks like crap, but it gets the job done. It is much more like a desktop browsing experience than on a mobile device. Built in ad-blocking is pleasant, but I would like to see a per-site removal of adblocking, as I like to support my favourites.
Pinball HD - This is just an amazing game. Wonderful graphics, 3 great tables and awesome physics. I find myself playing this all the time. For only $2.99 it's a complete bargain.
I've bought a couple of dozen Apps and these two are by far the best I've got and the ones I get the most use out of. I actually use a couple of free Apps more often (Solitaire & BBC News) but these two are definitely 5*.
One I really want to buy, but would like to read a real review (never sure whether to trust App Store reviews) is MyNetDiary. It looks good, and the website is good, but at $10 it's a bit steep for a whimsical purchase, especially as I've already spent a good $120 on Apps since I got this thing!