Covered here are those orchestral works that don't fit into any other convenient category.
Schumann wrote a number of overtures, both as stand-alone pieces or for his operas and other choral works (which I'm not covering). The two which I listen to again and again are the overture to his opera Genoveva, Op.81 (1847-50) and his Incidental Music to Byron's Manfred Op. 115 (1848-9). The Manfred Overture is a particular favourite of mine.
Manfred Overture Op.115
Genoveva Overture Op.81
Works for solo instrument and orchestra
This category includes three early unfinished piano concertos as well as the two works here.
Fantasy in C for Violin and Orchestra Op.131 (1853)
Written for the young Joseph Joachim as a precursor to the Violin Concerto during the manic and productive year of 1853, this is a very pleasant and lightweight exhibition piece for the soloist, in complete contrast to his other late works.
Fantasy in C Op. 131
Introduction and Allegro in D minor Op.134
Completed in less than a week during August of 1853, this was originally dedicated to Clara Schumann in celebration of their thirteenth wedding anniversary. Later that month, they met the young Brahms, who impressed them so greatly that the dedication was changed in his favour. This seldom played piece deserved a wider audience-
Introduction and Allegro in D min Op.134