I've read some articles that stress the importance of maintaining the online reputation of your company: so when you do a search for your company's name, the top results are all pulling up results that you have some sort of control/influence over.
For example, an online company should spend the time to create a listing in squidoo, facebook, flickrs, etc. Not only do you create an additional online presence, outside of your actual website, through these online resources, they can also provide other SEO and reputation-management benefits as well.
Some resources that come to my mind that are easy to establish and worth the time to do:
yelp - squidoo - facebook - myspace - flickrs - thisnext - wordpress (or some other blogging service)
That said, can anyone provide a list of the top resources that you've had a personal experience with that you control, advertise, and monitor and/or any other thoughts about this type of online marketing?