If you've implemented categories on your blog using Del.icio.us, you can do the same! Del.icio.us offers feeds for each of your tags, so using Feedburner is polish rather than necessity. If you're into this, you'd probably be most interested in the user/tag or user/tag+tag feeds as follows:
- User/Tag combo - del.icio.us/rss/julian/science
- User/Tag intersection - del.icio.us/rss/alan/music+dance
Filed in: rss feeds blogtech del.icio.us
Are you planning to put on some topic-specifc RSS feed buttons too? Maybe you could tag the URLs (eg http://del.icio.us/rss/MisterTor/pseudoscience) in delicious, using the tags "RSS_feed pseudoscience" or similar. That way, readers can browse feeds by topic (select "RSS_feed" tag on your blog or in delicious) OR when they pick a topic ("pseudoscience") the RSS feed will be listed as well.
Another side effect: since delicious make all your categories available as rss feeds, people could subscribe to your blog's micro-feeds!
http://del.icio.us/rss/MisterTor/RSS_feed
That way, people who are constantly wondering "Wow - what new spin-off feed will he hive off next?" can subscribe to the above URL, and as you create new micro-feeds for the blog ("kittens", "Zen" etc), they will be informed through this "master feed". Naturally, they can then subscribe to the micro-feed:
http://del.icio.us/rss/MisterTor/kittens
Or not. :-)