Firefox 3.5 provides option for clearing recent history. This can be accessed by pressing Ctrl + Shift + Del. You can specify the Time range to clear like last
hour, last two hours, last four hours, Today and Every thing. Similarly using the details drop down you can specify the information that needs to be cleared.
The different information includes Browsing & Download History, Form & Search History, Cookies, Cache, Active Logins and Site Preferences. After selecting the required time range and the details, you can click on the Clear now button to complete the action.