Before the trip, draw up an outline for an essay, short story, novelette, or other piece on a topic of interest to you.
During the trip, write it.
When you get back, edit the text and submit it to magazines/publishers for consideration.
Before the trip, settle on a graphics artistic project such as a book of cartoons, a pop-up book, or movie.
During the trip, draw the cartoons, sketch out the pop-up book, or storyboard the movie.
Before the trip, choose a software project that's never been done before.
During the trip, map out the block functionality, drivers, database interface, or whatever else the project needs.
When you get back, program the project and release it on Github as open source.
Get a book on sleight-of-hand and read up on the basics.
During the trip, practice the techniques with a deck of cards or a coin or a small item. (I enjoy knuckle rolls and rolling ball manipulations.)
Get a video of someone whose stage presence you like. Play 1-minute loops of the video over and over, mimicking the hand motions and gestures of the speaker while he talks. (I like James Spader, but everyone should have their own likes.) Practice until your own stage presence is animated and engaging.
Get an audio of an announcer whose style you like (I chose Morly Safer), and play 1 sentence loops of whatever they're saying over and over. Mimic their vocal variety, tonal variation, and tempo - especially the way they use pauses and emphasis to make points. When you have any one sentence down pat, switch to the next sentence. Continue until your own vocal presentation is as polished and precise as the speaker.
Choose an aspect of life that you would like to improve, or for which you think improving would benefit you, and then come up with a way to learn more or practice during your trip.