I saw one here...
65+ Vehicle modifications for better fuel economy - EcoModder.com
And a couple here...
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
I started out simple. In short time, what was "that's crazy" turned to "why haven't I always done this...." Also check out the search function for questions, and browse for ideas. A lot of great stuff here.