Hi Ammit,
I use Avidemux for simple editing, cutting, and mainly for conversions. It's free and available for all major platforms. It doesn't have transition effects, but it comes with many useful processing plug-ins for de-interlacing, adding subtitles, cropping, resizing, adding logos / watermarks etc. and it can use avisynth scripts. And it exports files in the appropriate formats for online streaming services such as YouTube. It is here:
http://fixounet.free.fr/avidemux/ A good alternative to this is Virtual Dub:
http://www.virtualdub.org/
For effects and transitions I just discovered Debug Mode Wax (
http://www.debugmode.com/wax/), which looks promising, but I haven't had time to play with it yet.
I also have bookmarked this:
http://jaycut.com/ - it is an online video editor, but I also haven't used it.
Hope this helps a bit.