Try Billing Boss from Sage Software (http://www.billingboss.com). Seems like it's what you're looking for. Plus, it's free!

It comes in 14 languages and supports multiple currencies. They have all the standard invoicing features, plus:
-Unlimited invoices and clients
-E-mail support (send invoices directly to clients)
-Full PDF support (send attached PDFs to clients automatically)
-Unbranded e-mails
-Data sharing (add a partner or bookkeeper)
-Track Cash Flow (payment recording)
-The ability to accept payments online via PayPal or their own payment services
-Support for taxes, discounts, and your own logo
-Mobile-friendly site (iPhone and Google G1 support)

They have other advanced features such as:
-Ability to accept payments with your emailed invoices
-Accept payments on your phone using a new or existing merchant account (www.paymentboss.com)

Full Disclosure: This author has been compensated by Sage. I am their Social Media Consultant but I was using their product well before they contracted me. They found me when I sent them an email giving suggestions about Billing Boss!