Glype proxy script is a free-to-use, web-based proxy script written in. It is open source, but it is NOT released as GPL or a similar license. Its license requires: either keeping the back link or getting a (paid) license.
Glype script has become very popular after PHProxy project ceased. Glype is similar to PHProxy, but there is one fundamental difference: Glype uses curl to retrieve web pages. In addition, compared to PHProxy, Glype has more caching controls.
On May 7, 2010, Baron Munchausen, the administrator of Proxy.org announced that he acquired Glype. (source: http://forums.glype.com/news-updates/1286-baron-acquires-glype.html and http://proxy.org/forum/1273292889.html)
Some tutorials for Glype: