On Sunday, I took part in a write-off event: write a fanfic under 750 words with the prompt "One Little Mistake." Writers were supposed to have one day to work on it, but I ended up doing mine in about 30 minutes, and submitting it moments ahead of the deadline.
Anyway, there are 21 total entries, which folks can read and vote on over the course of the next week. Given that all the stories combined total about 15k words, that's not exactly a daunting amount of verbiage. If you like reviewing, or if you've been looking for a way to try your hand at it in a low-stakes environment, why not try reading and rating these stories?
Also, if you're interested, I've got mini-even-by-the-standards-of-my-mini-reviews-reviews of all the fics here (and PresentPerfect's right below!). This is actually the sort of thing that got me started on ponyfic reviewing--I used to make a hobby of reading and leaving a one- or two-line comment on every story in the compilation posts on EqD, because I felt bad that many of those stories never got any comments at all... and three years later, here we are. Anyway, go check it out!