[rhombus]

If I want to hide my presence and actions on the Internet, I can do so in such a manner that it would be next to impossible for someone to track my actions.

From your ISP? Why be mysterious? Share the knowledge.

[taxcontrol]

I will point you in the right direction:

http://en.wikipedia.org/wiki/SOCKS
http://www.samair.ru/proxy/socks.htm

Do some reading and then follow this train of thought.

SSL or IPSec encrypted tunnel to a SOCKS server outside of the US. This is as far as the ISP will be able to see. That you contacted a server in some other country, period.

From that SOCKS server, you can surf as you please. Even ISPs on the destination side will only be able to track back to a site outside the US. Since the link between the two is held outside of the US, the logical linking of the two is much more difficult.

Further obscurity can be had via layered SOCKS accounts and/or further encryption tunnels.

[Centurion2000]

From your ISP? Why be mysterious? Share the knowledge.

Find an offshore HTTPS proxy and proxy all traffic through there.

[TomGuy]

One fairy easy method is a browser called TOR Park Browser.

It directs the user through other ISPs, usually in Europe. It is slow, but if you need some private surfing, it will work.

[cryptical]

From your ISP? Why be mysterious? Share the knowledge.

Check out Torpark:
Torpark (Wikipedia)