I'm working on playing the melody of Charlie Parker's "Anthropology" in all 12 keys at the moment.
As always, doing it sets of thirds. Today I worked it out in Bb, D and F#(not pleasant!) I find doing this means I can work it out in 3 keys a day and have that cycle of keys to practise in my spare time, rather than starting it in 12 keys and just giving up halfway through.
Tell us all in the comments what you are up to!