Sigma Lenses
The Sigma Lenses Website
Cokin Filters
The Cokin Filters Website
A very comprehensive photography website with user galleries, reviews, competitions and lots more.
Lee Filters
The Lee Filters Website
A premier images gallery website with forum and user galleries
Manfrotto Tripods
The Manfrotto Website
DSLR User Magazine
The Website of Digital SLR User Magazine
Nikon Europe Website
The Nikon Europe Website
The Official Canon Website