Though I've only been into anime/manga for roughly 2 years, I was only made aware of the whole fan-created abridged versions of a series at the London Anime Con last February. The ones on display, or used in "Dub That Anime" events were InuYasha, DragonBall Z and One Piece, none of which are shows that I'm interested in, but I like the improv style of gag jokes, and the smart editing that can make the humor work.
I stumbled across one today for a show that I love which is Mirai Nikki, and it's already been a big hit for me. Even the voice acting is rather impressive for an amateur production, and I'll definitely finish this one and explore others.
So as two questions to everyone:
1. What's your favourite abridged series?
2. What others would you recommend? If you want to recommend specifically for me you can find my best rated shows here, if there have been any abridged versions made for them: http://myanimelist.net/animelist/DragonBossk&show=0&order=4