Tekla Bimsight

Tekla released a free BIM software that you can use to load and inspect BIM models, in IFC, DWG and DGN formats. This indicates that it is not strictly BIM, but as you can do clash checking and inspect models, this seems a nice tool. They claim that you can use it to combine models from different disciplines and assist with information sharing.

It is only available for Windows.

http://www.teklabimsight.com