This is what we're doing at 10x Management (http://10xmanagement.com). I'm a YC alum and experienced web dev freelancer. I also play a lot of music so, through serendipitous connections in that world, met some music managers, and realized what they do for their music clients would be really useful for me as a freelance programmer.

So we started with them representing me -- taking care of the business end of my freelancing -- and it worked out so well that we've partnered to create 10x Management, to expand the model. I bring the tech experience, and they bring the talent agency experience.