FreshBooks Online Invoicing and Cleint Management
Freshbooks is awesome for the small business of contractors that needs to invoice his clients and track projects. The first 3 clients are free, then pricing plans accelerate after that. They broke the news to me over email when I asked that they have a plan not listed for 10 clients for 9.99/mo... Be sure to ask about it. It tracks your project times, creates invoices from your custom items, uses your custom logos on invoices, prepares estimates and tons more. It's goodness!

Oh, and if you sign up with the link i have above, i get stuff - so... thanks in advance :-D