So much fun!
Okay, so I've spent a bit of time over the last week thoroughly enjoying this three-sentence ficathon thing that 
rthstewart has going on over here.
It took me a while to jump in, but I'm glad I did. I've filled two or three prompts (four? I have no idea, I'll have to go find them and put them in here at some point), and even made some prompts of my own. I may even do some more.
Go have a peek if you're interested, it's not specific to any one fandom, and I really am having a blast with it.
Prompts I've Filled:
1. Avengers, Bruce/Natasha, so shock me -
vialethe
2. Narnia, Lucy and Peter (or Lucy/Peter), joy and strength -
starbrow
3. Narnia/Avengers, Susan/Hawkeye, the target - saoirse7
4. any, any, "This is the way the world ends. / Not with a bang, but a whimper." -
tiny_white_hats
5. Narnia, Pevensies, and as we move from dusk to dusk/what will survive of us is love/and even if it's not enough, it's something good -
vialethe
6. Any, any, you use your heart as a weapon -
betony
Prompts I've Given (That Others Have Filled So Beautifully):
1. Dark Is Rising/rthstewart's Narnia cross, Will + Susan, royal mien - filled by
pencildragon11
2. Narnia, Eustace +/ Jill, it seemed like a good idea at the time - filled by
wingedflight and
autumnia
3. Avengers, Steve Rogers, these little wonders still remain - filled by saoirse7 and
lar_laughs
4. Narnia, Susan (+/ any), never even noticed we're suddenly crumbling - filled by
vialethe
rthstewart has going on over here.
It took me a while to jump in, but I'm glad I did. I've filled two or three prompts (four? I have no idea, I'll have to go find them and put them in here at some point), and even made some prompts of my own. I may even do some more.
Go have a peek if you're interested, it's not specific to any one fandom, and I really am having a blast with it.
Prompts I've Filled:
1. Avengers, Bruce/Natasha, so shock me -
vialethe
2. Narnia, Lucy and Peter (or Lucy/Peter), joy and strength -
starbrow
3. Narnia/Avengers, Susan/Hawkeye, the target - saoirse7
4. any, any, "This is the way the world ends. / Not with a bang, but a whimper." -
tiny_white_hats
5. Narnia, Pevensies, and as we move from dusk to dusk/what will survive of us is love/and even if it's not enough, it's something good -
vialethe
6. Any, any, you use your heart as a weapon -
betony
Prompts I've Given (That Others Have Filled So Beautifully):
1. Dark Is Rising/rthstewart's Narnia cross, Will + Susan, royal mien - filled by
pencildragon11
2. Narnia, Eustace +/ Jill, it seemed like a good idea at the time - filled by
wingedflight and
autumnia
3. Avengers, Steve Rogers, these little wonders still remain - filled by saoirse7 and
lar_laughs
4. Narnia, Susan (+/ any), never even noticed we're suddenly crumbling - filled by
vialethe