A good site for evaluating longevity aspects of paper, ink combinations from an independent well respected research firm.
http://www.wilhelm-research.com/
A great site for archival inks, black & white and color software et al.
http://www.inkjetmall.com/
A nice site for the digital artist interested in fine art paper, software and printers.
http://www.digitalartsupplies.com/
Great assortment of paper particularly scores card stock.
http://www.redrivercatalog.com/index.htm
A large assortment of papers from the major manufacturers (EPSON,CANON, HP)
http://www.atlex.com/
Best place to find that clear sleeve to store your pictures.
http://www.clearbags.com/
Information on Piezography software and workflow.
http://www.piezography.com/PiezoPress/
Great source for Hahnemuhle, Moab and other fine art printing supplies.
http://www.lexjet.com/