Official Coldplay site

Unofficial Coldplay websites
Spiderwebs
The Blue Room
Bigger Stronger
Everything's Not Lost
Yellow
Coldplay Pictures
High Speed
Coldplayweb
Parachutes Are Trouble
Yellowvision
NME Coldplay Microsite

Sites with lots of bands (including Coldplay)
MusicZine
Too Many DJs

Coldplay Clubs

Coldplay Blue Room (Yahoo)
Coldplay (Yahoo)
Coldplay (eGroups)
Coldplay (NBCi)

Guitar tabs
Indiemusic.org.uk
Scarlet Monkey

Photography
Bigger Than Words

Music resources
Bandlink
Music 365
NME

Online ticket shops
Aloud
Ticketmaster
Way Ahead
Gigsandtours.com
NME Tickets
TicketWeb

Misc
Microsith
Skinz.org (make your desktop cooler than everyone else's)
Popex (buy shares in your fave bands... cool online game)
Surfmiles (get paid to do anything online)
BePaid (shows flash ads that you get paid to watch)