Excellent rundown of ways to practice forms (as if I expected any less....eeesh.)!!
Some additional things that I have used in the past:
Five Animals Forms : Using the various attributes for the animals, run through a form as each animal. For example: Do the form "tiger" style, emphasizing the power of the strikes. Don't worry about speed, stability or other concerns like that--think only tiger, only power, only attack.
Do the form "snake" style: concentrate on flow and on being fluid in movement.
"Dragon" style: compbine the animals as much as possible; work on blending speed, power, fluidity, stances, as much as you can--and emphasize breathing.
(This is really simplistic, but it gets the idea across, I hope!! I know there is much more to each animal, but you get the general idea).
Also, we have done "Forms in Chaos" at our school: You have a circle of students around the one doing forms. When he/she is ready, the student in the center does the salutation of the form we are working on and goes to it, any way they want to perform it (working tool/target, speed, etc.). The students in the circle can shout, wave their hands and feet, and generally try to distract the student doing the form as long as they 1) don't touch the student and 2) aren't abusive or crude in their words or actions. If the student in the center breaks focus or stops the form, they have to start over.
I have also done form "movie" style or "musical style": put some music on while you are working the form, and try to keep up with the "mood" and tempo of the music. I call this "movie" style sometimes, because I feel like this is one of those scenes in a MA movie...
A final one that my instructor is fond of: We run through a form facing front. Then he has us turn to different directions and run it again (corners, to the rear, etc.). Then he points us in different directions and has us run the form by the set (or by the move, for short forms). At some random point, he *may* say, "Okay, finish it up", at which point we can do the rest of the form.
Heh....just a few of the methods I have played with...
Peace--