Jason Calacanis on SEOs...
These are guys in really bad suits trying to get really naive people to sign long-term contracts. These clients typically make horrible products and don't deserve traffic--that's why they're not getting it organically so they hire the slimebuckets to game the system for them.
Note: There are some whitehat SEO firms out there I know, but frankly the whitehat SEO companies are simply doing solid web design so I don't consider them SEO at all. SEO is a tainted term and it means "gaming the system" to 90% of us.
This whole gaming of digg/Netscape/MySpace is being called SMO--social media optimization. That's the worst thing I've ever heard of. Anyone who hires an SMO firm is an idiot. The whole point of social media is TO BE REAL NOT FAKE!!! Just be yourself and participate... that's all it takes (and note, participation is not just putting in your own links, it's voting/commenting on/submitting other people's content too!).