There is an excellent blog over at BookEnds, LLC about whether authors should post work on their websites. Many writers are afraid work will be considered published if it shows up on their web page and then an agent or editor won't touch it. Still, sometimes you feel like a little kid jumping up and down and yelling, "Pick me! Pick me!" from the slush pile.
More and more author websites are publishing first chapters as a teaser and as it says at BookEnds, LLC, some agents are looking, especially if you comment on their blog entries. It's natural. I always look at blogs or profiles of people who comment on mine. After all, they must be cool if they are interested in my blog.
Agents are people too. They're curious about who reads their stuff, just like everyone else. So I'm leaning toward posting at least a sample chapter. Most agents and editors don't seem bothered by it, and it's worth it if I can generate some interest in the book from potential fans, as well as agents or editors.
I wouldn't put your beta draft up there, of course, but consider posting after you have graduated from that shitty first draft to the can't-put-it-down, groan-for-a-sequel, soon-to-be-bestselling novel. Wait till you have the book finished. You don't want to generate interest, get a response, and have to tell someone it isn't done yet.
Then comment on those agent and editor blogs and see what happens. As more agents and editors enter the blogosphere, it'll be more dignified that jumping up and down.