IZEA has a tough row to hoe. They compete in the part of social media where SEO meets sponsored blogging and tweeting. I'm not sure how they can differentiate themselves from services like Twellow, which provides some market data beyond what a basic Twitter account reveals. Bloggers who are tied to one advertising partner would probably love an open-architecture approach that connects them with multiple ad partners. The catch is that bloggers have to sign up to blog about . . . their advertisers? That's a pretty limiting deal; most bloggers publish because they love to speak freely. I think their offerings to publishers are a little complex, with free samples probably unnecessary and costly to administer.
They've only been publicly traded since this February and I suspect their IPO was premature given their net loss in 2011 was $1.8M worse than in 2010 (from their 10-K of Mar. 28, 2012). It's hard to control costs for a strategy that demands a lot of customization. Google mints money because much of its platform is customizable by users within strictly controlled limits.
Web 2.0 is a fun game to play but only a few of the hundreds of wanna-be players will end up winners. Quite a few social media optimizers and connectors will be bought out by the big players only to see their technology shelved (as Google did with Aardvark). These tiny companies can innovate but their technology is often perishable, because they have only a small window of opportunity to grow explosively before a big company tries to copy their model.
Full disclosure: No position in IZEA at this time.