Kazukito Yamushita has done some pretty impressive guitar versions of concertos by Vivaldi, Carulli, and Guliani, as well as guitar interpretations of many other famous works like Scheherezade and Dvorak's 9th symphony.
I quite like Mendelssohn's Violin Concerto in E minor rendered with a flute by Hungarian flautist János Bálint. Although I still think the original itself is insurmountable, I still love listening to this alternate version now and again and it's an impressive performance by said musician, in my opinion.
Since the piano is capable of such a range of simultaneous notes and melodies, I feel they're somewhat excluded from being easily adapted to a different instruments unless its from the same instrumental family. I wouldn't mind hearing Stravinsky's violin concerto played on a piano, but then again I'd be interested in hearing it played on almost any other instrument, simply because it's interesting to hear works we know well interpreted differently.
To answer the question, though, Sibelius' Violin Concerto is another that's quite fresh in my memory which I'd like to hear played in different instruments.