Not SEO specific, but I'm very happy with Podio as a project/client management solution. Takes a bit of getting used to, but does everything I need. Doesn't do billing, though, so it would depend on your particular needs.
I don't know of anything. Indeed, I don't even like any of the "all in one" toolsets as I find that (at least some of) the individual products are usually pretty weak. While I dislike the fragmentation, in the interests of maintaining standards I end up using a combination of tools and systems. I usually link to the extras via the project management system itself. Not perfect, and no doubt not for everyone, but works for me :)