Rowen and I just started reading Harry Potter and the Goblet of Fire. Throughout the past three books, I've been trying to give each character (except for George and Fred) a distinct voice and/or accent. In general, I try to hold to my best (which aren't all that good--except for Dobby) impressions of the actors in the movies with a few exceptions--I'm particularly proud of my over-the-top snobbish voice for Draco Malfoy. Unfortunately, the opening of book 4 included a group conversation in a tavern between a group of one-time characters. I thought that I was doing fairly well, when Rowen started laughing and said, "Dad, you made that woman sound like Ron."
Sadly, I'm not doing much better with my adventures with Vohnkar--the halfling (but don't call him that) barbarian in my D&D group. Partially in homage to Pippin for Lord of the Rings and partially because I have Vohnkar wearing a kilt (because he sometimes grows a tail when he rages), I decided to use a Scottish-like accent when I'm playing him. Sometimes, I get it without a problem, but more often then not, he ends up sounding Russian. I was also running an absent player's character today, and I tried to give his character a cheerfully youthful voice, but I ended up sounding like Dudley Do-Right (rather than trying to correct, I embraced it).
These little upsets don't stop me from trying to use accents, and having fun while I'm doing it.