Any plans to support the full R5RS numerical tower in TinyScheme? Or at least numbers with arbitrary length? Fractions could wait, but being able to do (* 123456789 123456789) would be a good thing :)
If there are no plans I might go ahead and try it myself. Things needed: a new "num" datatype (array/string based, probably), add, sub, mul, div, rem, mod, ... for this datatype, and the ggt function and another new datatype for fractions (consisting of 2 num's). Also: exact->inexact, inexact->exact, etc.
Not very difficult, only a lot of stuff to do.