Word study publications: The website sells some of the best publications for the improvement of your vocabulary (site includes description and ordering possibilities).
toyli.co.il: Looking for a regular, old-fashioned Scrabble set? This online Israeli-based toy shop is your best bet. Scrabble sets can be ordered via email ([email protected]) or phone (052-6664668). Recommended.
SamTimer.com: Manufacturer of round boards, clocks, tiles, racks, bags. Based in US.
Tilefish: Your One-Stop Shop for everything Scrabble. Based in UK - everything from sets, tiles and clocks to books and Scrabble-related games.
Zyzzyva: Michael Thelen's excellent word study programme, for compiling word lists, finding anagrams etc. The best I've come across (and it's free...).