I'd like to open a thread for sharing "tech" related tips. Everything what could be useful for others.

My favorites for computer-related tips:
http://www.online-tech-tips.com/
http://www.raymond.cc/blog/

Defragmentation, system cleanup:
http://www.piriform.com/ccleaner
http://www.piriform.com/defraggler

Battery status:
http://osirisdevelopment.com/BatteryBar/

Wi-Fi scanning:
http://wifichannelspread.codeplex.com/

Image editor:
http://www.getpaint.net/

Online PDF unlocker:
http://www.pdfunlock.com/

Wallpapers:
http://interfacelift.com/
http://www.vladstudio.com/wallpapers/