I used to work at a company which was eventually acquired by Siemens PLM (there were some intermediate merges and acquisitions as well). We had a pretty neat CAE (Computer Aided Engineering) product called I-deas - you could build a part then watch heat transfer or mechanical deformation take place under various forces and conditions.

Also it was funny how we found out about the acquisition. We showed up one morning and one person in next cubicle yells out "hey check out CNN, looks like we've been acquired". I was just an intern so didn't affect me much but other developers were pretty shaken by that.