I remember I did designed a Touchscreeen GUI in MultiFE which actuelly works for emulators and mame too... It can also show the mouse pointer.
Some Frontends can also use a mouse as a spinner like scroll, so you can scroll fast up and down.
All Frontends have been of course using keyboard and joystick in mind, but I guess this is for multimedia or such device where you have full access to a mouse (or trackball)?
Simple Touch Front End mightbeen another, but not sure it works with MAME (but should works for all others)?
I mean also I saw a mame plugin to Media Player Center as well, but not sure it touch/mouse freindly or not, its a year ago or such I saw that.