Angry Birds is the most addictive game i've yet to play on the iphone
TuneIn Radio...very good digital radio thingy but you'll need to be on wifi because 3g or edge is just a buffering nightmare.
If you play guitar then Polytune is very good. As is the ultimate guitar tab app.
Eirtext...if your on O2...gives your access to your free webtexts.
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