Recently, I have been searching the web for distant cousins, often discovering a great deal of genealogical information while doing so. Through trial and error, I have stumbled upon a pretty efficient way to do this.
The search engine I use is Hotbot (aka the Wired Search Center). Using Hotbot's SuperSearch, I can narrow down the search to mostly only relevant pages. Here's how.
On the SuperSearch form, select "the person" from the first pull-down menu. In the first space provided, type the name of the person you're searching for. Under "Additional Search Terms", type "genealogy" in the "must contain" field. A year of birth is also useful here (but drop it if you don't get any matches).
For example, to find genealogy web pages of cousins related to me through Nathaniel Harmon (born in 1654), I would enter "Nathaniel Harmon" in the first field, and "genealogy, 1654" in the second. This search yields 2 matches, "Pedigree Chart # 37: Harmon, Norton, Austin, Martin, Skinner, Huggins, Barber" and "Family Tree Maker's Genealogy Site: User Home Page Report: Report". I personally can't stand Family Tree Maker sites, so I skip that one for now, but checking out the other gets me in touch with relatives with whom I am currently corresponding via email. This form of search has yielded many hits for me so far, and I've barely begun.
Just remember, the further back you go the more likely it is that you'll find a relative who has bothered to post their information to the web. Also, remember that the web changes every minute -- if you don't find any links today, that doesn't mean they won't be there the next time you try (hotbot doesn't even currently have all of my pages indexed, so I don't even find my own pages when I search for someone else!)