Whether you need to package a single fragile ornament or fold an elaborate gift box, HowPack has an enormous number of printable paper folding templates for every kind of object and configuration you can imagine.
There are templates for boxes, tubes, dispensers, papercraft novelties like trucks and planes, geometric shapes, and even historical buildings. Each template is available as a JPEG image. Although JPEGs don't scale quite like a PNG file, since you'll only be using it as a template to mark your folds and cuts, a few jagged artefacts on a large printout shouldn't cause a problem.
The site lacks a search function but the way it is laid out makes it easy to quickly move through all the thumbnails of the templates. If you have an interesting papercraft site to share, let's hear about it in the comments.