Another great source for digital and video cables and connectors is Canare. Their cable is better than Belden and their connectors are very high quality, especially their true 75 Ohm BNCs for digital, video and digital video. The best place to buy Canare products is from Markertek, a major supplier to the pro-audio and video industry. They have good service and great pricing. Markertek ships from Las Vegas and New York. Note that Markertek has a full custom shop that can make any cables, patch bays, etc. that you may need. The best budget digital interconnect is D.H. Labs D-75 with Canare true 75 Ohm BNCs. More info on my Choosing Between Consumer Digital Audio Interfaces page. Canare also makes the excellent Star Quad balanced microphone cable, with clean polyethylene insulators and a highly-flexible, low-microphonics jacket.
Update: I've been helping a friend audition high end speaker cables. Frankly I was surprised at the differences between cables. It helps that the rest of his system is very high resolution with Spectral electronics and Dunlavy SC-V speakers. So far the best cables in my opinion have been the Nordost SPM Reference and Silver Audio. Both of these are low-impedance cables with excellent, if different, construction. In a nutshell the SPM Reference was extremely clean if a bit hard, and the Silver Audio was highly coherent and natural sounding if a touch soft. Neither is a perfect cable, but they are the best I've heard so far. Obviously cables are pretty system dependent so the best advice is to try them in your own system.
Another speaker cable possibly worth checking out is the Audience Au24. BD in Stereophile claims it's as good as Nordhost Valhalla which costs 4x as much. I have the nagging hunch the Audience is remarketed generic coax but the materials speak otherwise, while I know the Nordhost is excessively well made. Perhaps incredible would be a better description. Valhalla performance derives purely from physics, not snake oil. Though Valhalla is overpriced, you get absolute top quality materials and manufacturing and an outstanding design. In an Audio Asylum review Uncle Bob compares Audience Au24 to Kimver Select KS-3035 at 3.5+x the price and likes the Audience better.
For some comments about digital audio cables, please see my Choosing Between Consumer Digital Audio Interfaces page.