VSOP for exosatellites? (Io, Titan, Ariel, etc) VSOP87 (and the subsequent VSOP2000 and VSOP2013) provide reasonably 
accurate planetary positions while still maintaining a small file size 
compared to the Chebyshev polynomial files. 

VSOP includes our moon, but has anyone created something similar for 
other planets' moons (such as Jupiter's Io, Saturn's Titan, and 
Uranus' Ariel)? 

I'm thinking about trying to create something like this and wanted to 
check that it hadn't already been done.
Yes, there are several I know of for the Galilean moons, less so for other satellites.  One very good place to start is from the same organization that created the VSOP series, now called IMCCE.  Here is a link to their satellite ephemeris.  According to the Explanatory Supplement to the Astronomical Almanac, most of the other moons of Jupiter behave to chaotically to create a similar theory and numerical integration is required to produce accurate results.