The Word Detective
A very useful place ... like the list that I obtained recently from one of the journals at work.
I particularly liked the Star Trek essay on World Wide Words. The links on that sight are very useful too &em; especially the links to crossword dictionaries and crossword making programs.
One of the things that fascinate me is that people who create these sites all seem to have a sense of joy about their discovery of new words or new ways of looking at words and their meanings.

"Fascinating", as one of my favourite fictional characters might say *G*