Now I'm thinking about gnomes, gnomes gnomes. Some ideas on class abilities.
1. Tiny size: because they're very small, smaller than halflings (about "2 spans tall" so between 18 and 24 inches on average), they use d3 for hit points, but they receive +4 to armor class. That bonus is doubled if their opponent is larger than man-sized. They are pacifists by nature, and don't spend much time learning hand to hand combat, but they're tough to catch just because of their tiny size. Gnomes cannot carry large objects or wear heavy armor, which is fine by them as they generally eschew possessions anyhow.
2. Fluency: gnomes can understand and speak with all animals and elementals (level 0), sentient races/creatures (level 1), and even most plants (level 3) and inanimate stones (level 5). This is basically an empathic form of understanding. But they're illiterate (by their culture) and have to learn written languages per their Intelligence just like everyone else (obviously that only counts for languages that have writing, there's no written "wolf" or "birch tree," for example). They also must learn to speak angelic/infernal and alignment languages, as those do not come naturally to them.
3. Garden Wards: humans place tiny figures of gnomes in their gardens to protect them and defend against intruders, and this custom comes from the innate powers of real gnomes. A gnome can always counterspell, and therefore spell duel, as a cleric (based on personality). Their counterspells are always considered to be a defensive counterspell. Their spell checks are rolled based on their level (0: d12, 1: d14, 2: d16, 3: d20, 4: d20, 5: d24, 6: d24, 7: d24, 8: d30, 9: d30, 10: d30). Gnomes can also spellburn stats to use in a spell duel / counterspelling action.
4. Camouflage: gnomes are small and secretive, and able to stand motionless for long periods of time. They can hide just like thieves at level 1, and at level 4 they can invoke the power of the natural world around them to cloak allies within 10' in a similar way. This ability lasts for up to 3 hours per level.
5. Invoke the Purity of Nature: because of their affinity for the natural world, gnomes are intimately familiar with elementals and natural forces, and they with them. Elementals will not attack a gnome, even if ordered, though they will defend themselves if a gnome engages them. Similarly, a gnome may invoke the power of nature to cleanse taint and corruption from a thing (level 3), person (level 6), or area (level 9). This power is similar to a cleric's turn unholy ability, in that a gnome essentially banishes the corruption or taint from the thing, person, or area by rebuking it. The gnome rolls a d20 and adds his level and Personality modifier versus a DC of 15 (minor corruption/curse/taint), 20 (major corruption/curse/taint), or 25 (greater corruption/curse/taint).
6. Animal Companion: a gnome may take an animal companion similar to a wizard's familiar, although strictly nonmagical in nature. Many gnomes enjoy riding wild dogs or wolves, and a few of the more powerful have been seen riding polar bears or tigers. The gnome must bargain with the animal, much as a human would pay a hireling, although the animal will remain loyal to the gnome so long as the gnome sticks to the bargain. This is up to the judge, but typically carnivorous animals will demand to be fed meat regularly, and of specific or higher quality the more powerful the animal (e.g., polar bears demand seal meat at least once/week, tigers demand human, elf, or orc flesh once/week, etc).
7. Shape Plants: a gnome can sing to plants to cause them to grow in particular patterns. For example, a gnome can cause a tree to grow protrusions that are step-like, so he could walk to the top of the tree, or he could cause briars and brambles to grow in a thicket, to hide or shield him from prying eyes. This takes place gradually, but speeds up as a gnome increases in level. The plants grow at the rate of 1' per level per turn, to a maximum size (or affecting a maximum size) of 10' per level per day.
Gnomes think of themselves as guardians of the natural world, and as such, are almost exclusively neutral in alignment. They do get afflicted by some of the wanderlust that strikes halflings, though, and an adventuring gnome can be a valuable part of a party because of their powerful defensive abilities.