Re: History
If you are letting others use YOUR computer, then make sure you create a separate guest/standard user account for them; this ensures that limited settings are in place, and it will not allow any user on the aforementioned accounts to browse anything on your account (your files, cookies etc.).
If they are tech savvy, then i would also use the this free utility, CCleaner. It cleans all your temp folders, history, cache, cookies etc.
Hope that helps. 