I wasn’t aware of this website until recently. Wikifonia is a large collection of scores covering many music styles,including rock,jazz,and Broadway musicals. All scores include chord changes and many of them also lyrics. As as important,the community behind the website is very active,and 2-3 new songs are added each day.
What makes Wikifonia really powerful –and interesting for woodwind and brass players –is the ability to transpose the music for Bb and Eb instruments,or to change the key by any given number of halftones. Each song can be downloaded as a PDF file and exported in MusicXML format. You can decide the page format (A4 or US Letter) and even render the page in Braille!
My thanks to Mike Powell for bringing this resource to my attention.