Really, I think the best names you'll ever find are in foreign languages dictionaries :)
I mean it-just as Shinichi-san posted before me, colors are great option (I have pets named Kuro, Shiro and Gris as well, so I was all "oh, lol, somebody things just like me"), but then again, my first unicorn there is named tear in Japanese because I like the sound of this word. (If it ever become possible here to get twins, I'm gonna name them Twilight and Dawn in Japanese, just because they sound great, too)
Next thing with names is, they sound great if there's and "el", ""F" or doubled "L" in them, for example: Ellen, Melf, Fael...whoops, I mean, in my native language "e" is read close to how "a" is read in English, so that names sound soft but wise.
Oh, and last thing with languages-why not use numbers? I mean, I don't know if anybody wants to name their pets- or characters- let's say un, troix(1,3 in French) or eins (german: one), but come on! *gets into Japanese mode* Roku(6) or Kyu(9) or even Hachi (8) sound cute, aren't they?
Dancing in the dazzling light, countless feathers goes to a white place...
They become endless bond, leaving fading ache...
"Yakusoku no hane~White feathers"