http://www.tartybikes.co.uk/index.phpA bit specialised but the best choice of sprockets for those of us that use s/s cassette conversions and some fixed stuff as well.
http://www.singlespeed.nl/catalog/index.phpSome useful stuff. One of the first places I saw an Eccentrica (hope I spelled that right) eccentric bb conversion. The shop part of singlespeed.nl which is now just a blog, it appears. One of the sources of Surly stuff if you are in continental Europe.