LARPs:

LIONE

Prophet's Fall

Epic Adventures

Madrigal

Prophecy

Radiant Dragon

The Isles

Dragon Crest

NERO Mass

Stargate LRP

Knight Blades

SCA related links:

Clann O'Choda

Game related links:

Mayfair Games

National Game Week 2006

Rio Grande Games

TotalCon

LARP related sites:

General info about what you need at any LARP:

http://www.arsmagicae.com/

IFGS: 

http://www.ifgs.org

LarpLand:

http://larpland.com/

LARPA:

http://www.larpaweb.net

RPGnet LARP Forum:

http://forum.rpg.net/

Shade's LARP List:

http://www.larplist.com