Like many people, I have wanted to make my Pi use a USB wireless adaptor, but there seemed to be so many around that I didn't know which one to choose.
On a complete impulse purchase, I bought the following from Amazon:
To set it up, from command line I did the following:
sudo apt-get install firmware-ralink
Then followed this guide from the words: Add adapter definition to network config - eg: sudo vi /etc/network/interfaces - add the wlan0 section:
I used Nano as my text editor rather than Vi, as I find a lot easier, if you are the same just use sudo nano wherever it says sudo Vi in the guide.
Follow to the end, and you should have a wireless Pi using the Debian Squeeze distro for less than the cost of a Mocha-Latte-Vento thing.
Steve