This site has several privacy tools that you can use to prevent others from know what you are doing.
They have a free Web Proxy tool that allows you to surf without being easily tracked.
Their top product is a VPN that will hide everything you do from the computer it is installed on, regardless of where you connect to the internet. (your home, or a Wifi hotspot)
As with any tools, there is not 100% protection, but with these tools, someone will have to go through a LOT of hassle to get the information.