diskimage.c – Library used in QtCBM to access D64 image content, by Per Olofsson

Commodore Free – A Modern Magazine dedicated to Commodore machines.

Carlsen Electronics– Very knowledgeable in the repair of all things Commodore.

C64.com – Fantastic place for demos and D64 disk images.  Interviews and more…

Lemon64 – An excellent review site with screenshots and ratings.

Retro Inovations – Home of JiffyDOS. An absolute must for speeding access to the 1541.

Bombjack – One of the absolute best places to find great reference books on Commodore machines.

GameBase64 – Another great place for disk images with searchable game database.

C64Copy Central – In-depth page on making the cables used for transferring images with QtCBM

OpenCBM – This is the open source software that forms the basis of QtCBM.

DeepSID = A giant library online of SID music classics from games/demos. Built-in player also!