Newegg and friends crush a patent troll
arstechnica.com
arstechnica.com
I'd also add, they've added a tremendous amount of information in the PC parts buying process, from really in-depth videos from manufacturers talking about their products and how they differentiate different tiers to the reviews and relatively pain free rebate and sale system.
If they ever added a "I'm building a PC" and it cross checked items for compatibility to streamline the purchase process (so you don't buy the wrong kind of RAM or video card or whatever) they'd absolutely dominate the custom PC parts industry.