What's your favourite Ipod touch / iphone app?

Tweet

I am so excited - I just got a bunch of vouchers trough in the post from a survey company. I saved for a long time to get all those vouchers. So tomorrow I am going into town after work and buy myself a 3rd generation Ipod touch. You'll laugh, but I already downloaded quite a few free apps as I heard they are so good. Any tips on favourite apps?