In my search, I came across two that look fairly promising: Mona the Vampire and Edgar and Ellen.
Mona Parker is a young girl with a vivid imagination who fancies herself a vampire and saves her town often from supernatural phenomena with her friends. This series is French Canadian and didn't air originally in the United States but did show in Canada, France, and even Poland. Luckily, if you want to give series a go in English, it IS available on Netflix.
For those of you off the NA continent, I'm not sure where you'd find it. Sorry. >_<
Edgar and Ellen are 12 year old twins who live alone in a Mansion on the outskirts of a good-goody town called Nod's Limbs - where they spend all day creatively pranking each other and building gadgets from the nearby junkyard.
This series has a very Addam's Family feel to it, albeit aimed at a younger crowd. This series is also available on Netflix and Nicktoons.
It originally started as a book series for kids and those are still widely available for purchase.