What sort of games do you like? My favs are Civ Revolution, numba, Lux DLX (version of Risk board game), Peggle, Bejeweled, suduko, lemonade tycoon, sim city and stick wars.
Facebook app and Tweetie app both good (latter for twitter obv).
"Aroundme" good is you live in a city (lists nearest ATM, restaurants etc). Rightmove also good if you're nosy!
If you have Sky+ then there is an app which allows you to record programs remotely. Flizster tells you what is on the the cinema and gives ratings, clips etc.
Ocado for shopping. Ebay too.
If you live in London there are a couple of apps which help with planning journeys by public transport.
Urbanspoon gives you local restaurant choices, by rating, cuisine or price. Google and Google Earth are must haves. pUniverse is a cool app which shows you details of the night sky.
Toodledo is a good one for todo lists.