This website is by far my favorite place on the Internet when I want to find portable applications of any kind. As the name implies, everything you’ll find here is 100% free and portable.
One observable plus that The Portable Freeware Collection holds over every other competing portable applications directory is that it makes sure to offer as much information about each application as possible.
The Portable Freeware Collection is the place to go if you’re looking for the largest source of portable applications.
Another nice MakeUseOf article on portable freeware, this time listing some of the author's favorites. Includes articles from here, PortableApps, and elsewhere.
Topic update: MakeUseOf.com is still supporting portable software, here's an article from 2019 I've had laying around for quite some time -- some interesting picks therein...
There are a LOT of portable apps out there. Which ones are worth using? Here's our master list of the best portable apps that don't require installation.