The following sites are great places to get ideas...
Berthoud High School Make For Good - this maker space makes with a purpose
School Library Journal's Teen Librarian Toolbox: Makerspace page - GREAT resource
MakeSpace Tools - Colleen Graves' list is comprehensive for K-12, explore her site for all the ideas.
Manhattan Make-a-Thon - 76 page PDF with loads of ideas and standards, too.
Make it @ Your Library - loads of ideas to make with simple materials, site maintained by librarians.
MakerSpaces.com - they overcharge for some of their materials, but they do have some great ideas.
North East ISD Maker Space Homepage: In-depth maker space page with ideas and resources.
Exploratorium - so many science ideas...
WSWHE BOCES - when I need the words to justify my Maker Space, this website has wonderful articles and resources to dig into.