What are these "Character lists" all about?

I have RSS feeds for so-called “Vanity Searches” to see where my name & blogs are mentioned. They sometimes show up in “Character Lists”, like the one below, but I’ve no idea what these are used for. Can anyone enlighten me?

mrhangman : character list
character list
Holds? When someone is on hold, all that means is no decisions on the character will be made UNTIL that app. is in. This is not a first come first serve community. The best applications are chosen. Be sure to hold your character! If you don't and still work on an application, it's more than possible that we'd fill the role before you even have a chance to get one in. Limit on holds is five. Comment here if you'd like a character held. Holds last for 48 hours with a 24 hour extension if needed.

Key
Italicized names are being held.
Character names linked or struck out are taken.

Gryffindor
Abercrombie, Euan
Bell, Katie
Brown, Lavender
Coote, Ritchie
Creevey, Colin
Creevey, Dennis
Dobbs, Emma
Finnigan, Seamus
Frobisher, Victoria

mrhangman : character list
character list
Holds? When someone is on hold, all that means is no decisions on the character will be made UNTIL that app. is in. This is not a first come first serve community. The best applications are chosen. Be sure to hold your character! If you don't and still work on an application, it's more than possible that we'd fill the role before you even have a chance to get one in. Limit on holds is five. Comment here if you'd like a character held. Holds last for 48 hours with a 24 hour extension if needed.

Key
Italicized names are being held.
Character names linked or struck out are taken.

Gryffindor
Abercrombie, Euan
Bell, Katie
Brown, Lavender
Coote, Ritchie
Creevey, Colin
Creevey, Dennis
Dobbs, Emma
Finnigan, Seamus
Frobisher, Victoria