FindMeATune.com is a great free service that allows users to find songs in several genres just by entering a few words of the lyrics.
Since the site searched the internet to retrieve the lyrics, the options are quite wide, as I found lyrics by Leonard Cohen, Regina Spektor and the Beach Boys as well, but it seems to host only words in English. When you click in the ‘View Lyrics’ button you get redirected to some other site that has that song’s lyrics. When you cannot find lyrics through the search engine, you can post them in one of the forums the site hosts, or alternatively mark it as a ‘mystery’, and then somebody with better memory than yours comes and marks it with the correct artist and provides the lyrics, and since you can subscribe to RSS feeds, just get notified whenever somebody cracks the mystery. The site is currently being refurbished, so users are encouraged to submit their ideas for improvement at the site’s blog, and per what can be read most complaints have to do with forum features. 
