Well, they're not nearly as awesome as Opal Island, but I've made bunches of maps all or mostly with the little trackpad on a laptop. I use PhotoPlus - Serif has a reasonably capable free version as a teaser, and their full-up versions aren't anywhere near as expensive as Photoshop. But I wouldn't hesitate to use either The Gimp or Inkscape instead - both of which are free.
If you're losing fine motor skills, maybe a mid size tablet is what you need - is there one that can be set up as a touchpad, for finger control, instead of for digitizing pen?
Oh, and in case I missed giving you rep for Opal Island when it first came around, here's a smidgen - that is an amazing city map!