ubuntu - How can I change my public IP address?

I'm looking for a way to change my public IP address. You know, the one that other websites see.

I know what I'm looking for is basically a proxy server, but I don't want to use a proxy for 2 reasons:

1) It slows me down. 2) See reason #1.

I'm using Ubuntu 9.10, I'm connecting to a public WiFi network (the ISP is Time Warner Cable). I'm getting my IP through DHCP.

Thanks for any help!