I've recently heard of some spin off games from the PSone RPG, Final Fantasy 7. I thought I'd post the news here.
Advent Children
I think most of you will have heard of this one. It's an animated film that takes place after Final Fantasy 7 (2 years afterwards). The animation on the trailer is extremely impressive but I have no idea about the story line. Sephiroth is back as the villian and that's all I know.
[edit] Having got more info, it seems that Sephiroth is not the Main Villian. The shots of him walking through the fire are probably a flashback to FF7.
Even though the film is not yet finished, Square received a special invitation to show the film at the Venice Film Festival. It was also recently shown at the Montreal Film Festival. The film is also supposed to be available for the PSP when it is finally released. The trailer can be viewed
Here
{Edit}
Two more trailers can be viewed on the
Official site. Enter the site and got to Trailers. Trailer 2 is in English.
Before Crisis.
This is a Mobile Phone game, which takes place before Final Fantasy 7 and seems to be about the Turks, possibly about their rise to power. Not much is known about this game yet although Square Enix have released two screenshots.


Not bad for a mobile game. Information can be found
Here
Dirge of Cerberus
This is a PS2 RPG which takes place one year after the events of Advent Children. The main character is Vincent Valentine, one of the two optional characters from FF7.
Information about this game is found
Here
These Spin offs are being made to "Complete the FFVII Story and explore the entire FFVII world".