One thing Teamwork did well was allowing you to create companies and then assigning projects to those companies.
This works in literally the same ways as spaces, but in their instance you had different tabs for Links, Notes, Messages, Comments, People & Settings.
You could also add their company logo, contact details etc too.
I'm finding it a little bit awkward not having a central repository for all my client info in each space.
Currently I'm having to make a separate project called "account info" and recording any account info there.
Although is okay, it's a bit of hack that could be improved.