Update Feb 20th 2015: Added the PHP version of Pollen Buddy.
I wrote this library a year and a half ago when I was working on an Android pollen-tracking app for allergy-sufferers like me. There was no publicly available pollen forecast APIs, and all the existing Android apps for pollen tracking were not aesthetically pleasing.
A few people expressed to me their interest in using it, and so I decided to open source it.
Note, the library is very experimental. I recommend against using it in a live production setting, since Wunderground could change their CSS and HTML by a character and the library would stop working.
You can use this library anywhere the MIT license permits. Please kindly reference me on your website or app when you use it, and if possible, contribute back patches when/if necessary.