A quick Greasemonkey script, before my hard drive dies:
This started from a rewrite of Matt Biddulph's Radio 3 script to use the new GM_xmlhttpRequest function (which allows Greasemonkey to do XMLHTTPRequests across domains so Firefox's security settings don't have to be changed), then ended up making something a bit different. It could certainly be improved, but it works for now.
The script adds a list of del.icio.us tags for that page, a list of pages tagged with the artist name and a tag posting form to the sidebar of audioscrobbler artist pages (example page).