Making the Next Step

The company that I work for currently carries over 500+ different types of parts for boilers and pumps. Being that there are SO many different items, it makes it quite hard to push all of them up to the top. My question, what could be done to take this site to the next step? Because I feel that with the wide variety of items that my site is getting watered down in the search engines.

www.boilersupplies.com

I currently have about 8-10 other domain names that are doing absolutly nothing. Should I break my main site down into sections (say, Valves, Pumps, etc.) and make make a domain for that specific section?

It's certainly a confusing bunch of links on the front page. If it was me (and this is only my opinion) I would use the front page to display all the latest deals and then split the site into something more like a Search Engine directory structure. If you've got some spare domains then that may well help. Hope this helps.

Nick