I've just ordered one of these
256Mb memory cards for my phone, was tempted to get more storage (up to 2Gb!) but I don't really need it as I'm not planning on lugging a huge music collection around with me (I don't have one for a start) and I'm trying to keep it cheap.
The plan is to lob a few podcasts on the phone so that I can listen to them whenever I get the chance, still really annoyed that the mp3's don't play over my Nokia car kit but there really isn't anything I can do about that. If I'm still in the job this summer I'll be changing the car and that'll sort it out.
Next I need to suss out getting files on and off the phone, it doesn't come with a data cable and I'm too tight to buy one. I've been using infrared but it's slow, I have a Bluetooth dongle thing somewhere so I'll see if I can get that set up. I could get a cheap card reader but I don't fancy whipping the back off the phone all the time to get the card out...