1. There are no margins in the domain industry. Start thinking about building a hosting company. Your site is cool, but weebly.com and heroku.com are real businesses. I work full-time for Facebook, not IDS. (BTW, Facebook is hiring people like you, message me at http://www.facebook.com/beau if you're interested.)
2. It needs to be faster. For example, to squeeze another few hundred milliseconds out of our search, we built a distributed search infrastructure described here: http://instantdomainsearch.com/articles/faster_domain_name_s...
3. You should search names listed in the aftermarket and include them in your results. I've worked with http://www.buydomains.com/ for several years, and am happy with them. I can make an intro if you'd like.
4. Consider extracting words and doing a basic thesaurus search. We're doing something like that at http://instantdomainsearch.com/suggestions/
Hope this helps!