essay: Thoughts About Wands by Amy Z.

Most magic is done using a wand. It is possible to cast spells without using a wand, but for most wizards results are unfocused (CR). Wands are created from wood with some magical substance at its heart. Wands are classified by means of four characteristics: length, type of wood, quality of motion when waved, and type of magical ingredient. In Britain, the most well-known wand maker is Mr. Ollivander (SS5, GF18). His shop, Ollivander's (Makers of Fine Wands since 382 B.C.) is located in Diagon Alley. Another European wand maker is Gregorovich (GF18). When a wand is damaged or broken, it's effects can be unpredictable, even if patched together with Spellotape (CS, esp. 16). 

some famous wands and their characteristics
Harry Potter: holly, 11", supple, single phoenix feather (from Fawkes)
Fleur Delacour: rosewood, 9 1/2 ", inflexible, veela hair
James Potter: mahogony, 11", pliable (excellent for transfiguration)
Lily Potter: willow, 10 1/4", swishy (nice wand for charm work)
Voldemort: yew, 13 1/2", single phoenix feather (also from Fawkes)
Hagrid: oak, 16", rather bendy
Krum: hornbeam, 10 1/4", quite rigid, dragon's heartstring
Cedric Diggory: pleasantly springy, 12 1/4", single unicorn hair
Ron's new wand: willow, 14", unicorn tail hair

NOTES:
Both Cedric and Ron have wands with unicorn tail hairs in them. This is a bit disturbing because of the following exchange from SS:

"Yeah," said Hagrid, glancing up, too. "Listen, I'm glad we've run inter yeh, Ronan, 'cause there's a unicorn bin hurt -- you seen anythin'?"
Ronan didn't answer immediately. He stared unblinkingly upward, then sighed again.
"Always the innocent are the first victims," he said. "So it has been for ages past, so it is now."