getting all (or representative sample of) artists on last.fm

I'm using the last.fm API to get information on a set of artists, specifically the number of "listeners" (e.g. 732.4k people listen to Deerhunter). Ideally, I want this information for every artist in last.fm's database, but there doesn't seem to be a method to get a list of all artists. I can settle for a representative sample of artists on last.fm instead, but then the question is how to generate such a sample. Any suggestions?

Thanks, Ben