Gnomes are a really excellent choice for arcane spellcasters. I've seen people swear by dwarves for sor/wiz, but gnomes have the main benefits of the dwarf, plus small size, plus extra spells, and they lose Strength instead of Charisma for it.
Half-orcs make good fighters, barbarians, clerics, and druids. Half-orc rangers are really good, too. Although their net power level is lower than other races on the surface, there are ways to maximize their advantages and minimize their penalties. You just have to rely on the Strength and not worry about losing skill points or Charisma bonuses. That's partly why half-orc clerics are good; clerics don't rely on skills to be effective, and they have a number of ways to be customized so that turning undead is less important than buff spells and conbat prowess.