I whipped up something similar in Go recently. There's no README yet, but it uses cgo to link to ImageMagick for resizing, and serves up a folder of jpgs.<p><a href="https://github.com/georgebashi/pugholder" rel="nofollow">https://github.com/georgebashi/pugholder</a>
(edit: you can see it running at <a href="http://pugholder.com/" rel="nofollow">http://pugholder.com/</a>)