Is there an alternative to Shazam, but for OS X?
Solution 1:
An alternative is Tunatic. It has a handy little window with a sound visualizer:
Once it identifies the song, it displays the name and artist:
And takes you to a link where you can download it from iTunes or buy the ringtone version:
Solution 2:
Since your question stem from the fact that Shazam was only available on mobile platforms, today would be best to answer with this link and the news that Shazam has a desktop version for Mac OSX as well.