Sorax Reader is a Free PDF viewer. It has a small size, fast launch speed and a lot of features. There is no need for installation (it can be started directly from any kind of storage device - CD, PenDrive, etc.).
The PDF Creator and PDF Convertor supplied by PDF24.org works with all Windows programs and has a lot of features - create PDF files from almost any Windows application, re-order pages, merge, split, and password-protect your existing PDF files.
Notepad++ Portable is the handy Notepad++ text editor packaged as a portable app so you can do your development on the go. It has all the same great features of Notepad++ including support for multiple languages and an extensive plugin system, but there´s nothing to install.