We have done this a couple of times in my Seminary class, and it is always so fun! Use this to review material you've already covered or material that students already know very well. In our class, this ends up very silly, so it's best done at the very beginning or very end of class.
I've done this two different ways: as individuals and as a group.
INDIVIDUAL: After explaining to my class that I was going to have them summarize the story of the birth of Christ in poetry. To keep it short, I gave students just 4 minutes on a timer to write whatever they could. I then read them the poem I wrote to get them started:
On a donkey
Inns too full
In a stable
A baby born
A star arose
Race to see
In a manger
Would I run?
Would I fear?
Would I tell everyone?
When my students did this I had a few read their poems out -- the last kid ended his with "Peace out, baby Jesus." I laughed so hard I cried.
GROUP: Another time I explained to the class that the book of Lamentations is written in acrostic form, meaning that each part of the poem begins with a different letter of the Hebrew alphabet. So after the style of Lamentations, we did an acrostic poem that was Bible themed as a group. Each person chose a letter and wrote a sentence that dealt with the things we'd learned so far in our study. As a group we'd write a couplet to rhyme with it that started with the following letter of the alphabet. It was fun and served as a reminded of what we've learned so far.