Just a quick note that I've just done a very quick pass through the users list and removed all the users which had a name that looked like it was trying to sell Cialis (or similar pharmaceutical), and had never posted a legitimate comment (ie: one that actually made it onto the site, rather than being automatically flagged and confirmed by me as being spam). It was around a hundred accounts in total.
If I've accidentally deleted your account during this process, I'm very sorry! Please feel free to re-create your account in the usual manner.
To try to ensure that I don't have to do this again, I've enabled a few extra sanity checks during account creation which should stop bots from creating user accounts and taking up my time on another big purge in the future. Crossing fingers. :)