If you have some time - why not port Sage?
 

Well, I don't have time to do it (I'd love to have it), but if you do - you may consider porting SAGE to Maemo - a CAS system that's faster than Wolfram Mathematica!

See sagemath.org

Re: If you have some time - why not port Sage?
 

For a while there I thought you meant the accountancy software.

{cold sweat}