Well, you could always take a cue from our favorite IKEA hack of all time and use them to fuel a fire... but not only does burning pallets lack the elegance of the ad hoc bow drill (in the above hack), there are any number of reasons not to scrap them for firewood.*
We've seen from at least a few pallet-based design projects, including upcycled chairs and a full-fledged office, not to mention our own pop-upexhibition design. Among the pallet facts that we picked up along the way—some 700 million pallets are manufactured each year; North American standard pallets measure in at 48” × 40”—we were interested to learn that the EPAL-spec'd EUR-pallet comes in at different dimensions and standards.
It so happens that the 1200×800mm2 Europallet, as it is colloquially known, is suitably sized to span the (active) tram tracks that criss-cross certain cities around the world. Whereas several stateside and Italian streetcar systems run on 'broad gauge' tracks—wider than the 1435mm standard gauge that also turns up in the U.S., Canada, Australia, Great Britain, Germany, etc.—the taxonomy also includes narrow gauge tracks, including a one-meter width in cities such as Antwerp, Basel, Belgrade, Bern, Frankfurt, Geneva, Ghent, Helsinki, Zürich to name a few. (Different widths are named after different locales, including Russian, Irish, Iberian and Indian, all of which are broad gauge; see the full list here.)
And while trams are certainly a practical mode of transportation, the tracks can be a hazard to certain smaller-wheeled vehicles such as bicycles or skateboards. Which brings us to Tomas Moravec's pallet hack:
While the Slovakian artist has created many performative works of sculpture, installation and video art since he made the Duchamp-meets-Alÿs piece in 2008, the video went up just a few months ago. The brief description notes that Bratislavan trams run on felicitously narrow 1000mm-wide tracks: "A new transport vehicle brings change into the spatial perspective of a passenger in motion and generally changes the life of the city, through which the pallet can run, guided by a map of the city lines." (We have to assume that it would technically work in any of the cities listed above as well.)
*Regarding burning pallets, they're widely known to burn well, albeit at very high temperatures, but the general consensus is no-go; according to one source:
I was burning pallets last year until my research revealed that most shipping wood is treated with one or more of the following: fire retardant; insecticide; fungicide. The arsenic treatments were easy to spot being green; now copper compounds are used. Insecticides are not easy to detect. Fire retardants result in a brownish or rust colored stain. I have noticed that sometimes even stickers (for under bunks of lumber) are treated. I thought that I had discovered a gold mine when I saw pallets for countertops made of 4×4 oak 10' long with 3' cross members, until I saw that telltale brownish stain. I was heartbroken! In other words, err on the side of caution when selecting shipping wood.