First, a little background on things.
There is a project by the name of TOR (The Onion Router) — initially sponsored by the US Naval Research Labs but now by the Electronic Frontier Foundation — whose aim is to provide a means for its users to communicate anonymously over the internet.
The anonymity of the user is preserved by letting the packets sent by a user’s machine go through what the TOR developers call a TOR ‘cloud’ — a private network where the path the data takes is chosen randomly. The end effect is, if somebody tries to read the data as it comes out of the TOR cloud, it would appear to them as something that came from a server from anywhere else in the world.
Quite a feat, considering that a lot of the project is supported by volunteers.
Now, everyone does not need every communication done by their network to go through the TOR cloud, especially since most users would only be doing web surfing every now and then. In addition, using the TOR client in a commodity machine (a low-end machine at home, if I might say) would perform really slow since it consumes a lot of the machine’s resources.
To address this issue, Hacktivismo released a modified version of the Firefox browser, named Torpark.

Every communication done by the user would then go through the TOR cloud, which in effect renders browsing activity anonymous.
The current released versions are Windows applications, though Linux users may still be able to use it, as it works flawlessly under WINE.
I ran Torpark though WINE in my Ubuntu box at home. The only thing I noticed is that browsing activity is slow (For reference purposes, I got an Athlon 2600 with 512Mb of memory). I don’t recommend it for those who wanted to browse media-heavy sites. This may be more suitable for people who post at forums and blogs.
Get it at the Torpark website.