A fanlisting is simply an online list of fans of a subject (in this case for mosaic kakera) that is created by an individual and open for fans from around the world to join.
There are no costs, and the only requirements to join a fanlisting are your name and country. Fanlistings do not have to be large sites (although some are), they are just a place where you can sign up with other fans. TheFanlistings.org is the original (but not official) web directory for fanlistings, dedicated to uniting the fans.
Description from tfl.

Mosaic kakera

Title: Code Geass Hangyaku no Lelouch ED2 Single - Mosaic Kakera
Artist: SunSet Swish
Street Release Date: February 28, 2007
lyrics: romanji/english
download: full single
Tracklist:
1. Mosaic Kakera
2. Kagayaki
3. My Pace ~Premium Live Ver.~ Recorded at Shibuya BOXX on 15.Nov.2006
4. Mosaic Kakera ~CODE GEASS Ending Ver.~
5. Mosaic Kakera (Original Karaoke)