Paymo
I personally use this for the time registration and invoicing.
Invoicing your clients based on time registration is super easy.
Also comes with a free iPhone app.
http://www.paymo.biz/wp-content/themes/paymo/images/paymo_screenshot.jpg http://www.paymo.biz/wp-content/themes/paymo/images/paymo_screenshot.jpg
(source: paymo.biz)