Michael Robertson, best known for his work on MP3.COM, Linspire (nee: Lindows, prior to Bill Gates' deciding that he was going to crush another company) and SIP Phone, has recently gotten into Skype's face with the Gizmo Project.
The Gizmo Project is aimed directly at Skype on a feature-by-feature basis, but using standards-based design, rather than a proprietary locked-in system that ONLY Skype has a potential to benefit from. VOIP "should" be open to everyone, and Gizmo is designed towards that end. To be honest, that's the main feature that will push it over the top in the end, I'm sure.
It's beta at the moment, but well worth looking into. You'll be AMAZED at the call quality--even over a 56k dialup connection!
Now, you'll need a mic and speakers to be able to use it, but most folks have those on hand already. For those that don't, they've already tested some out, and offer links to recommended products at http://www.gizmoproject.com/accessories.html
First things first, of course...You've got to get a copy!
Check out their web site for more information at: http://www.gizmoproject.com/
Aside: Since "Gizmo" is merely a working title, they're accepting suggestions for a new name for the system once it's out of beta. I've submitted "IMaculate" myself and it's been accepted, but the final word isn't out on whose suggestion will eventually be made permanent. Feel free to think up and submit a new name yourself!
