In my capacity as Poeta "refers to herself in the third person" Atlantiae, we had three entries into the englyn milwr challenge. I'd prepared fifteen tokens (Welsh poetry tied up in little scrolls) so clearly I was hoping for a few more. But it was on the order of the response to the other bardic challenges of the day and, even better, the quality of the entrants was great. We had a gentle for whom it was his very first public performance of his poetry - and it was a fine poem! I told him he should do it more often in the future.
Personally, I answered the bardic challenge in honor of the king, on the theme of inspiring warriors to battle. I sang "To War!," a marching song I composed nearly spontaneously on the field at Pennsic. It is dead, dead simple and meant to encourage non-bards (e.g., fighters) to participate. It goes like this:
To war! To war! [My unit] goes to war!
(Insert a brand new verse here), [my unit] goes to war!
(Repeat until you've marched to where you need to be, or you're bored with it)
I've sung it with "Atlantia," "Storvik" and "Blackspear" variously in the "my unit" spot. Verses can range from the typical ("Our shields defend the kingdom," "Our spears are sharp and wicked") to the humorous ("My armor's really sweaty," "I can't see in this helmet") to the totally off-topic ("The sheep are getting nervous"). Roughly 7 syllables, roughly iambic, but whatever. No rhyme needed.
Not only did the populace join in on the repeating parts, but they contributed verses, too! (His Majesty kicked in the sheep example, even.) So happy! Vivat for the brave people of Highand Foorde, willing to extemporize in public!