Handguns & Ammunition Forum: http://www.handgunsandammunition.com/
Hi Powers-Handguns Blog: http://www.hipowers-handguns.blogspot.com/
US Firearms: http://www.usfirearms.com
Actions by T: www.actionsbyt.com
Shooter Solutions: www.shootersolutions.com
Mec-Gar Magazines: http://www.mec-gar.com/index.html
Hi Power Magazine FAQ: http://www.sff.net/people/pff/oldstuff/magazines/bhpmagfaq.htm
Bullet Expansion Testing: http://stevespages.com/page8f.htm
Byron's Hi Power Disassembly Instructions: http://www.drivehq.com/file/df.aspx/publish/bungib/PublicFolder/guns/detailstrip.html
For discussions on "stopping power", here are some sites in which different opinions are expressed:
http://forums.stoppingpower.net
Choices for On-Line Ammunition: