Bamboo Invoice

BambooInvoice is free Open Source invoicing software intended for small businesses and independent contractors. Our number one priorities are ease of use, user-interface, and beautiful code.

Features:
<ul>
<li>Uou are in control. BambooInvoice sits on your server. Its your data. You never need to trust your invoicing data to anyone else, and you can get it out of the system easily.</li>
<li>BambooInvoice is easy to use, and easy on the eyes.</li>
<li>BambooInvoice is actively used and developed.</li>
<li>BambooInvoice is built atop modern coding standards. Its a XHTML-strict, WAI conforming, CSS using treat!</li>
<li>BambooInvoice is internationalized. Currently it is available in English, French, German, Dutch, Romanian, Spanish, Portuguese, Bulgarian, Swedish, and Italian with new languages being added all the time.</li>
<li>Built on the excellent CodeIgniter project.</li>
<li>BambooInvoice is released under the GPL.</li>
<li>You'll be the coolest kid on your block if you use BambooInvoice.</li>
</ul>

Go to http://bambooinvoice.org/

See also these related projects.