Platform: Windows XP/2003 (might work with older too)

Now that I'm heavily into virtualization and doing a bunch of physical to virtual (P2V) moves, I end up having NIC conflicts on IP addresses with abandoned NICs that will never make their way back into my system. Of course Windows says "you already have this IP address on another adapter" when I set my new NIC as a virtual machine guest to the same IP as the old physical adapter had. So how to delete the old adapters? It's not like I can put them back in (it's a virtual machine now!) and remove them from device manager. Here's the process:

Drop into a command line.
Type in "set devmgr_show_nonpresent_devices=1"
(don't use quotes, we just set a shell variable)
Type in "devmgmt.msc" This will launch the Windows Device Manager Console.
In the Device Manager Console, from the "View" menu, select "Show Hidden Devices".

From here you can select the old NICs or other devices long gone from your system (the icons will be somewhat lighter than valid ones) and uninstall. Note, really really bad things can happen if you remove something you need, so only take out the NICs you know you can blow away.

Platform: Linux, Mac OSX, Windows - Firefox

Wondering where the cache is at? Type about:cache in the address bar and you'll get info on the path and be able to view content info as well. I searched Google for a while, and maybe this is a beginner tip for most, but I had a bear of a time finding it. Tip: On Windows it's buried in the local profile Application Data folder.