Best DIY tweak?

What is the best inexpensive tweak, you've discovered?

I agree with you on your tweak effectiveness (i.e. less things powered at home, no interruptions, lower background noise etc. etc) BUT unfortunately Rdylan meant inexpensive and that's where the thing goes sour......
One of the stranger tweaks is to make sure all media is stored vertically, this includes CDs, LPs, books and video cassettes. Makes a nice improvement, esp. if you have a lot of CDs, etc. (This tweak courtesy of PWB Electronics.

~ Cheerio