Speaking for myself, I find races fun when playing as a member of one race feels different (for reasons other than role-playing) from playing as a member of another race.
Modifying numbers that are relevant to combat (especially to every combat) can only take you so far before combat balance goes right out the window. This makes it hard to build races that feel distinct in play without building uber-races that are simply much better than the alternatives.
One way around this might be to give each race the opportunity to learn certain skills or spells regardless or what their class is. As long as you can put together an interesting set of these skills and spells, you can produce a race that will feel mechanically different in play.
Maybe this is already the case to some degree? The webpage says, for instance, that Dwarves can see in the dark and that Martians have some sort of ESP, but it isn't really spelled out.
For example, for the 8 races that are presently in use, the package might be something like the following. The benefits of a race shouldn't become redundant if combined with any particular class, so there should ideally be a Rogue skill, a Caster skill and a Warrior skill in every race package. I haven't made sure that this is so below - in fact, there are all kinds of things wrong with this list, but it gives the basic idea of the sort of thing I'm talking about:
Centaur
Charge
Kick
Sanctuary
Trample
Dwarf
Infravision
Pick Lock
Tinker
Elf
Bow
Identify
Sneak
Faun
Charm
Drunk
Sneak
Gringo
Firearm
Mount
Mounted Combat
Riding
Indian
Antidote 1
Forage
Tracking
Martian
Foresee
Fortify Mind
Meditate
Spacewolf
Detect Invisibility
Detect Poison
Trap Aware
Tracking