Your book/story will stand on its own merits. I don't see how people quoting or linking to you would be relevant information for an agent. Unless of course it proves that you are an expert on whatever subject you are writing about. If that's not the case, I personally would not mention it. The agent will be interested in your writing, and whether he or she feels it is marketable to publishers. Beyond that, or any special expertise qualifying you to write what you write, they honestly probably wouldn't care. At least that is my understanding.
*Note: The only way I could see an exception to this would be if these thousands of comments could somehow assure you of a ready-made readership that would clamor for your book immediately. Not sure how you would be able to ascertain that, though, since you just found this through a generic Google search.
**Note the second: This isn't meant to detract from your ego-surfing. I think that's nifty you have so many hits on your screenname! I just don't think an agent would find it relevant in a query letter. At any rate, good luck!
