These pages have items that you can download and save in your galleries.

http://www1.center.k12.mo.us/edtech/SB/collections.htm
Everything from simple machines to zoo animals.

http://www.mathvizza.com/Smart_Board_Galleries/index.htm
Math Galleries Grades 6-12

http://exchange.smarttech.com/search.html?m=08&
SMART Exchange has over 30 Gallery Collections