There are many ways to seek the right SEO company for you.
1) You can search on the keyword phrase you want to rank well for, and find the top ranked sites, then dig deep to find out who they hired (if they hired anyone) to make that happen. 2) You can go to SEO Consultants and search by a lot of criteria. 3) You can go shopping at an SES or WMW conference during exhibitor hours. 4) You can go to the forums and post a RFP (request for proposal) 5) You can go to a directory listing of SEO companies or search on "seo" 6) Go to a local directory like Craigslist
Members at Cre8asite Forums are discussing this now.
Some related topics we covered in the past on this subject: - Outsourcing Search Engine Marketing & Optimization? Questions To Ask - Hiring an SEM: Is it Hard? - Stuck with a Bad SEO Company; Here are Some Tips
Forum discussion at Cre8asite Forums.