I got it working with the native drivers from http://rt2x00.serialmonkey.com, but it took some doing. I had serious stability problems with the version 1.0 drivers from Ralink, but I upgraded to the 1.1beta drivers and it worked fine. The driver comes with a graphical configuratoin utility which seems pretty nice, except that using the statistics tab causes it to segfault on my system. Haven't figured that out yet.

I also had some problems with Slackware setting up the card. Apparently /etc/rc.d/rc.inet1 isn't as flexible as it should be. For some reason, the driver insists on calling the interface ra0 (changing the alias to eth0 didn't seem to work), but the network init script assumes all network devices are named eth#. I basically ended up rewriting that script.

The serial monkey rt2500 driver from cvs compiled easily and proved no problem. The driver available from the ralinktech site woudn't compile on my PC.

It's easy to set up once you go there :
http://www.methods.co.nz/doc/ralink-2400.html

I only had problems because of my inexperience with iwconfig. rated 9 because using dhcp didn't work and I had to resort to a static address for my machine.

Well nothing to say against really, cheap readily available, supports monitoring mode etc....
It took me over two weeks to get it working here's why:

when doing lspci if you get

00:0e.0 Network controller: RaLink: Unknown device 0301

then the 0301 at the end means that the card uses an rt61 chipset not rt2500(like it's written at the top of the page), nothing wrong with it but it won't work with the rt2500 driver!!

Really good card, IMO. As said before, it has open source drivers, which make it relatively easy to install on linux (you can find the drivers at http://rt2x00.serialmonkey.com as said above). It even works 'out of the box' on many distros I've tried like Ubuntu, Elive and Dreamlinux. Fr other distros you have to manually install the driver, but as long as you have the kernel headers for your kernel, the installation will be painless.