What program should I use to edit my photos?

I have PhotoFiltre and PhotoMud. I really want Photoshop but just CAN'T afford it. Any free editing stuff you'd recommend? I mostly want to enhance, sharpen, brighten, etc… I don't really like "pre-made filters", I like to control the settings…
I have a Nikon D5100. I don't like the Nikon editing software, though.

Added (1). I tried gimp about a year ago… Oh dear. It was too blah and confusing for me!

Gimp = free photoshop clone.

Gimp is a brilliant, free, open-source program for Linux, Mac and Windows. I have been using gimp for a while now, it is almost as good as photoshop. GIMP stands for GNU Image Manipulation Program.
Hope this helped.

Alaina, iPiccy photo editor is definitely for you. You'll find there everything you need (all that basic editing tools) and much more for free.

Citrify, iPiccy, PicMonkey, Ribbet, FotoFlexer or Lunapic are great all round web based and FREE editing tools. Adobe, makers of the expensive Photoshop, has a free website version in Photoshop Express. If you are a former Picnik user than Picmonkey and Ribbet will be your best choices.

http://www.edit-photos.net
http://www.squidoo.com/...oto-editor