Funded Today is one of the more well known agencies, but perhaps the most notorious as well. Only use them if you have budget to risk and are already successful. They do take 30% of the total amount you raise.
Crowd PR is a public relations agency, people on this website seem to have some very strong opinions about them.
Jellop is similar to Funded Today, but with a better reputation and a commission structure where they only take a percentage of what they raise (not the total amount. The draw back is that they are only effective with certain types of products.
Blazon PR is a public relations agency, and by the looks of their website and case studies, I'd say they do pretty good work. It's a premium service though.
Matix Labs is a facebook advertising agency. Not much of a track record other than their youtube testimonials. They are founded by the same people who do the "Nomatic" bags -- so I believe this agency is their funding source for their products. Something to beware of right there.
Agency 2.0 is perhaps the largest marketing agency. Their website says they are full service, meaning they do all facets of marketing (including content and video production). May be a little overkill for most projects, and I have read articles that their fees run as high as $50,000.
Enventys Partners is just like Agency 2.0. They used to go by the name of "Command Partners". It looks like they partnered up with a product development firm, and now people pay them to bring their rough ideas to physical products which are crowdfunded. So they do absolutely everything, but it makes me wonder how good they are at particular facets of marketing - if they offer services a la cart.