Firefox 3 plus, now 7, seems to have an incessant memory leak. IE and Safari decrease over time when not active but FF continues to grow, then freezes.

FF 7.01 currently. Memory usage in Taskman continues to rise to somwhere between 160MB and 380MB then FF freezes. IE and Safari memory usage also increases during usage, but after leaving computer idle overnight the memory usage decreases (clear cache helps). FF memory doesn't decrease when fallow.