The top SEO firms have bad reputation in public, don't accept new customers on the net and fuck about promotion! You need an invitation (if you can pay them) to be accepted as a client.
Most ad agencies have thier own internal SEO.. but personally I like some of the smaller firms like Mindspring who give better personalised service and dont try the one mold fits all approach..
As said earlier, if budget isn't an issue, such companies goes for in house marketing and SEO team. I don't think their is any such thing as Top SEO firm, it depends on your needs. A local seo firm can be top seo firm for you as they can come to you or you can go to them to discuss things
The top SEO firms are those who got higher PR and rank high with other search engines. Don't be fooled to hire SEO company that don't have even PR 4 website.
Easy There are alot of B.S. firms out there. Search SEO optimization in google and the top ones know how to do it.
If you are at issue with my opinion then, by all means, offer another.. but don't squawk at me like a parrot please. No, thank you. Nigel
I love bruceclay.com for all kinds of internet marketing services and rupizmedia.com for website designing.