Best Invoice Tools?

I'm setting up my own company soon.
What invoicing tools you guys use for your web business?
Any recommendations?

What type of company are you talking about?

Web Design / Development.

I'm looking at FreshBooks currently. Anyone used it before?

Microsoft Excel works great for simple invoicing, but for really running a small business I don't think there's any real competition to QuickBooks.

All my invoices are online, in PHP...with instant emailing etc..