Holy crap can you guys not get the iPhone on PAYG in the States? My fiance bought me my iPhone outright as a birthday gift, and I get free internet on it for 12 months, and the calls and texts are at the exact same PAYG rate that I had on my old phone. I hardly ever call on my phone, and send a couple texts a day, so £20 usually lasts me well over a month. Even paying the £10/month for internet after the free period is up will still save me money, as I found I send way more emails than texts these days...
Some of my favourite apps are:
Moonlight Lite (free Mahjongg tile game)
Solitaire City Lite (awesome free solitaire game)
TVGuide (UK tv listings)
Tube Status (see which tube lines are currently screwed)
Convertbot (really well done unit conversion app)
Day Tides (tide app with a curve and allows you to mark specific heights, like the point our boat grounds out)
Actually, all of those are free. I think the only apps I ever paid for are Tetris and Sims 3, but both of those have more issues than the free ones above!