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All I know is Ashampoo Snap.

puu.sh

press ctrl+shift+4

Print Screen + Paint ^^

I use one like that called Gyazo, it's similar to what you described.

Fraps? 0_o

Imgur. Print screen, then Ctrl+V. Can crop after upload.

picpick !

ALT+PRNT SCR for current window only ;)
Greenshot
PicPick
SnapIt Screen Capture

If you are using Windows Vista or higher, you get the Snipping Tool from Microsoft.

So much choice!

I'm developer of ShareX: https://code.google.com/p/sharex

It can do exactly what you want, with one click you can crop area and upload it to imgur, dropbox etc. and have url in your clipboard.

vvcap

Screen Grab Pro Deluxe, been using it for a couple of years already

clipper

I used to use lightshot.

Try snag.gy

Lightshot or Gyazo.

Windows has snipping tool, which will let you drag a box over whatever you need to capture. There is also Cropper, a free tool which does the same thing with a couple more features.

ShareX - just use hot-keys to take screenshot (whole screen / rectangle selection / free hand, etc.) and it auto-uploads image to hosting of your choice (with possibility to connect accounts), then it copies direct image link to clipboard. You can also upload text files (to pastebin etc.) and any other type (dropbox, etc.).
The only disadvantage is that we still can't edit images with it.

MWSnap 3 works fine. Not really into all-in-ones.

I like GIMP, but it's probably a bit overkill for what you're talking about

I like gyazo

Oh, didn't read that you already saw gyazo. My bad

Awesome Screenshot is what I use, and I'm quite happy with it. It's quick and efficient. It also lets you edit your screencaps, and then it gives you the option to upload them to one of two sites. One of which is a temporary upload that doesn't ask you to sign up for any services, and the other is more permanent but asks you to make an account there. Both work quite well. :)

Greenshot is pretty neat

If I want to create a screenshot as a file on my PC, I use Fraps and I have the screenshot hotkey bound to print screen so I don't have to bother with the whole open paint thing just to make an image. Now if I want to create a screenshot with a url I use Gyazo. It doesn't really get any easier than that.