Maybe you're interested in building a TC as well, or maybe you just want to check out some "plasma porn". Here are some of the best Tesla/high-voltage websites I found:

Information resources

Safety is paramount
Check out the TC Mailing list (plenty links here too)
The .HV forum
Tesla Coil Builders of the United Kingdom
VoltNet has basic theory and links
Hot-Streamer.Com hosts dozens of Tesla sites
including the great Terry Fritz's. Check it out.

Solid-state coiling

Solid state Tesla Coils by thedatastream.
He's got bricks, and I'm afraid he'll use them.
Jimmy Hynes, builder of the mighty DRSSTC.
Currently the most powerful SSTC in the world.
Richie Burnett (great spark gap stuff too)
Jan Wagner SSTC design guide
Derek Woodroffe (he's actually built an OLTC)

Other TC stuff

Matt Behrend has a great Tesla Coil theory website
Sam Barros has a great mini TC
However, Steve Ward's mini coil kicks its butt.
Richie Burnett has advanced in-depth theory
Jan Wagner has a good design guide has some pretty extreme TC action
Gary Lau has two fine Tesla coils and some
tremendous spark pictures.
Check out Tesla Technology Research's scale model of
the Colorado Springs transmitter. It gives sparks 55 feet
long! Run away!
Lightning On Demand: Makers of the famous "Electrum" coil
and your gateway to the West-Coast-Techno-Art-Mad-Max-
Destructo-Geek scene
kVA Effects
Tesla Coil specialists, lightning effects for TV, film, etc.
Watch the nightclub scene in the movie 'xXx'
The incredible Trashy Tesla: A Tesla Coil made entirely
from dumpster divings.
Jochen Kronjaeger's HV pages: Good information on
transformers etc.
Mike's Electric Stuff
HVFX: British company that do Tesla coil effects
Home of "Thor", Europe's most powerful coil
Legion Electric
These guys sell ready-made Tesla coils. Legend has it that
founder Steve Rodway once accidentally touched a live
pole pig.
Read about his pole pig encounter here
Did you know that Tesla coils were once tried as a
"cure" for Gonorrhea?
And finally a splendid collection of someone
else's links!