Dia Shape Repository
Additional shapes (often called symbols, objects or stencils) that can be added to your Dia toolbox. The following shapes are available:
There are several options to install the sheets and shapes from the Dia Shape Repository.
Diashapes is a small tool to download and install the above mentioned shapes
dia-shapes is a Debian package with all sheets and shapes from the Dia Shape Repository.
Standard Dia objects
Dia comes with an extensive set of preinstalled objects. The following is a small sample of it: