Another--subtle--promo idea is to put some sort of promo link in your signature file. Depends on how you do it, but as an example I hang out on guitar websites, talking shop with everyone, not bugging them to visit my site. In my signature (which is below, I think) I mention how there are virtual band jam tracks at my site. Within a couple months of NOT promoting I noticed the hits & downloads on my site double. Then all these guitar players started emailing, asking if I had anymore tracks!
The trick is to hang at an active site where there's a subject being discussed that interests you. People appreciate the chat, notice The Fixx link in your sig and inevitably click on it.
Music, stories, etc.