http://code.google.com/p/iphonefs/
Still beta, but this can enable alot of interesting apps, like syncing etc, without using iTunes.
Another IM client, but seems to have halted in development, in the wait for Firmware 2.0 and the SDK
http://www.iphoneskinning.com/2007/11/native-iphone-currency-converter.html
Want currency but not a new application? Use the Stocks application for it!
Place to search for any applications for iPhone.
http://touchmods.wordpress.com/
Voip on iPhone. Need to use the headset to work. Seems also that Jajah will make a voip application (will only work over Wifi. Cheap voIP providers:
hawkin 