We've included another open-source project in 2SexyContent - the (probably) best image resizing tool available to asp.net today. The ImageResizer is from Imazen, all is documented on http://imageresizing.net/. Here just some basic samples so you understand the potential and how to use it. Raphael also wrote a blog how to use this with tokens and razor.
This is the 5 MB original image.
(shrink to max width 200 or max height 200).
Constrained Two Ways
?h=200&w=200 (creates a 200x200 pic w/white space)
?h=200&w=200&mode=pad (creates a 200x200 pic w/white space, same as no mode)
?w=200&h=200&mode=max (creates an image that's 200 wide)
?w=200&h=200&mode=stretch (200x200, distorted)
Cropped - The best Choice for Precise Designs
?w=200&h=200&mode=crop (ensure full 200x200, cuts rest, like facebook)
?w=200&h=200&mode=crop&anchor=middleleft (or topleft, topcenter, topright, middle..., bottom...)
Enlarge if Necessary
?w=200&h=200&mode=crop&scale=both (or down, canvas - here not visible because pic too big)
Change Background Color if not Transparent (jpg)
?w=200&h=200&bgcolor=ff0000 (or any other color for non-PNG, non-GIF)
More Features / Documentation
Using in your Templates
...is super trivial. First example is Tokens, second is Razor