I've been learning and "playing" more and more with Linux based tools such as BackTrack which includes all the commonly used tools in one bootable Live CD. BTW, most of the best tools are Linux based... so in my opinion if I want to protect, I must know my enemy!
I was utterly amazed at the speed and ease of cracking into a WEP based wireless network... I have understood for years not to use WEP encryption, but I had no idea how easy it was to crack! A 13 year old with a laptop could be on your network now; using your bandwidth, or going into your shared folders. I setup a dummy router for this of course. It was cracked and I was using its Internet and changing router configuration within minutes!
I also tried cracking my own WPA encrypted wireless... Which I thought to be more secure. As I found out... it wasnt!
I do not use a word for my password, ever! I use a mix of typically upper and lowercase with numerals, some passwords I add special symbols to as weel for more security! My first attempt failed... a quick check of the huge word list I used contained a dictionary and a list of commonly used passwords and my pw of course wasnt in it. On my second try, after editing the word list and randomly adding my pw into it; I then cracked my WPA encryption in under 20 minutes!
I now run a WPA2 encrypted wireless network!
I have used older tools like BackOrifice
(in the day), BackTrack
(and similar tools for getting Windows passwords), and others. I find them invaluable tools in my consulting business. I use them for those situations when I am repairing a system and the user forgot to give me a password, or isnt available, or has lost/forgotten/changed it.