It has modules for vendors (so you can track how much you owe them) and clients (how much they owe you), and employees (including expenses).
I basically collect all the receipts through the year, do my own quarterly VAT and then have the bookkeeper do the annual reports, integration of all the companies and the actual filing.
I don't send out a lot of invoices and I don't have a lot of stuff I buy on the company so that is relatively easy to do.
If it's useful to you, I use freckle (http://letsfreckle.com) and/or google calendar (see http://blog.logeek.fr/2009/11/27/how-to-use-google-calendar-...) for time-tracking/invoicing.
Not the prettiest, or easiest to use, but once you get used to it and over the learning curve, its actually plenty useful and powerful.
In a nutshell, the user thinks in terms of invoices, customers, suppliers, payments, etc.. and Sage takes care of the rest and produces a full set of accounts.
You'd want to get some accountant to help out initially (I did), as some of the concepts in the accounting world can be a little unintuitive and then you end up with unbalanced accounts.
I just started looking at http://outright.com. I've been playing with it for the last 30 minutes or so. Seems like a pretty nice system. It sucked in all of my PayPal history from last year, and even properly expensed PayPal's fees. First service I've used that did that.
I've been using Quicken Mac for over a decade, but I need something more, given a business change, so I'm going to try out Quicken Online. (One of the main features I need is check printing, and most of the online accounting packages don't support that.)
Also, prefer it over freckle since freckle is WAY more expensive ($40 for Billings vs $12/mo for Freckle)
Your best solution might depend what tax jurisdiction you're in, though.
Used GnuCash for 5 years, and whilst it was OK, Xero is a hell of a lot nicer to deal with.