i've done this before- personally i think you can pick ANY theme.. ones i've used/saw
sometimes things are moved up, but sometimes things are added - and those little things have the goals written on them.. i let the kids 'make' 3-4 goals... like 'i will read 80 words in less than 2 minutes with 4 or less errors (it is one thing our reading program did regularly) or 'i will stay on green for 2 days out of 5' - 'i will get a spelling test grade of 70% or higher' or whatever they needed to work on - they'd review their goals and were sure to hit them eventually so they were very encouraged. you know how that part works- making the goals higher and higher...
monkey- add a banana
dogs- i took photos of the kids each wearing this headband that had a dog nose/forehead and ears on it, then cut out the head and placed them on cartoon dog bodies.. then they added their goals, written on little bone shaped paper, into their dogfood bowls..
i made the kids faces 'flowers' and put them on top of long stems.. they added leaves
space ships- that time the goals were all the same so they moved their ships over to the next planet each time they made that math goal.
along the same lines with the same goals- each classroom had to 'become' a state - so as they moved along, instead of planets, they moved along popular/famous landmarks of that state
last year we did national monuments...
whatever you theme is, i honestly believe you can make a goal with it.. PM me if you want other ideas