Firefox has a keyboard shortcut to clear the cache: Shift-Ctrl-Del.

IE has none. But in IE7 you can create a shortcut that does the job.

1. Right-click your desktop, Create shortcut

2. Paste in this string as program: RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 8

3. Name it something nice. I have dragged into my quick launch bar for fast access.