It's amazing how much software is required to manage and run a professional services company. In addition to being good at architecting and developing client solutions, there is all of the other business related "stuff."
I've been a user of 37signal's Backpack for quite awhile. We've used it extensively to organize aspects of previous projects and I continue to be amazed by its usefulness.
We've now branched out to use BaseCamp for the project management side of things as well. Again, it's very simple but that's part of its elegance. What I'm very excited about is the use of Cashboard in our operations. It's not a 37signals product, but it has certainly been developed with that paradigm in mind (plus it also integrates very well with BaseCamp.)
Cashboard is an excellent tool for managing timesheets, estimates, invoices, and accounting-related information. Best of all, it's accessible anywhere and that's a very good thing for people on the move.
We deal primarily with Microsoft tools and it's been suggested that we "eat our own dog food" by using Microsoft tools exclusively. Luckily the ALT.NET movement is coming along nicely and people are realizing that it's best to use the most appropriate solutions that the community has to offer regardless of which company built the product.
… and the community has a lot to offer. If you want to be amazed, take a look here at the various issue tracking systems available. Tough choices but due dilligance has its rewards .
Richard Obuhowich