At any given time I have 20,000 -30,000 domains in my software, so building automated backlinks is essential. I started using Link Exchange a couple months ago. basically, you install the software on your server, then you upload a list of your url's with anchor text via csv. Check your options and start exchanging links. You can chose to have your links shown statically or dynamically on other users sites, you can also chose which search engines can see the links, so you can show the backlinks to yahoo and msn, but not to google for example. Anyhow, it's powerful, inexpensive, and it does what it says.