MegaSquirt
MegaSquirt - http://www.bgsoflex.com/megasquirt.html
MegaSquirt manual - http://www.megamanual.com/index.html
MegaSquirt forum - http://www.msefi.com/index.php
MSExtra (for running wasted spark directly from MegaSquirt)
Documentation for building/upgrading to MS Extra - http://www.msextra.com/
MS Extra forums - http://www.msextra.com/forums/index.php
Software
TunerStudio MS, the most user friendly tuning software - http://www.tunerstudio.com/
Books
An excellent book covering everything you need to know - http://www.amazon.co.uk/Performance-Fuel-Injection-Systems-Cramer/dp/1557885575/ref=sr_1_3?ie=UTF8&s=books&qid=1289519114&sr=8-3
Suppliers (parts specific suppliers are listed on the Parts page)
UK Supplier of MegaSquirt ECU, looms etc - http://www.extraefi.co.uk/
American supplier of MegaSquirt kits - http://www.diyautotune.com