There are also the concerti grossi, which are a baroque excuse for having concertos without a soloist. I'm not sure if the Italian concerto gets excused for using a different, baroque meaning for the word... Okay now I'm confused, the Brandenburg concerti have multiple soloists each, so are they proper conceri grossi or regular (aria-tic) concerti?
Regarding the list we are compiling (of psuedoconcertos), add the Chopin Andante Spinato & Grande Polonaise, and the Liszt Hungarian fantasy.
Another thing - the Alkan concerto for solo piano isn't a concerto in either sense of the word (baroque or otherwise).