MyImgur is a portable tool which can take screenshots, share those images (or any others) online via Imgur, and manage your Imgur account if you have one (although that's an optional extra, and not at all necessary).
The program works best when batch uploading images. If you want to share a bunch of photos, just drag and drop them onto MyImgur and they're automatically uploaded, no login (or anything else) required. Clicking Uploads displays a list of those files, with their Imgur links. Right-click in the History window, and you can open all those links in your browser, or copy them to the clipboard for immediate sharing with anyone else.
Screen capture is more basic, but still good enough if you'd like to share something on your desktop. Click the Capture button, click and drag to select a freehand rectangle on your screen, and as soon as you release the left mouse button, your capture is uploaded. Pass the link to someone and they're able to view it immediately.
MyImgur can pre-process captures to reduce their size. You're able to set a lower resolution, a preferred format and quality, or reduce image quality if the file is too large.
If you have an Imgur account then the program can log in, create, empty or delete albums, upload to your choice of album, set an image as "favourite", and more.
MyImgur is extremely portable, too: it's written in native Win32 code, so doesn't even require the .NET framework.