CAD software manufacturers are trying to ease the burden of the recession by offering trials of their software or reduced cost versions. Here are links to those software. If you have others, or you have any comments on these offers, please post a reply.

AutoDesk
Here is a specific URL you can use to get free Autodesk software. It does not require that you have a school email address. Please note, this is for a student version.
http://students.autodesk.com/?nd=or&id=1078&ic=yvDGIVLrhx

Select this option for the non student version, 30 day free trial offer of any Autodesk software. Be sure to select the right software type from the dropdown in the upper left corner before filling out the form.

SolidWorks
SolidWorks is offering a 90 day Engineering Stimulus Package. This has numerous learning resources, including tutorials, videos and forums.
http://www.solidworks.com/sw/esp/engineering_stimulus_package.html

Pro-Engineer
These guys are a bit stingier with the software. Students can register for a free student version here: http://www.ptc.com/appserver/wcms/forms/index.jsp?&im_dbkey=86840&im_language=en. For others, you can buy it at a reduced cost on their web site. Note the limitations.