A Virtual Appliance Server is often the quickest and easiest way to have a look at a lot of these Open Source Projects. A Virtual Appliance Server has all the required software installed saving the time required to set them up. The images below are not always suitable for using in live environments but are a great way to see an application. There are a few Virtual Server Solutions (Vmware, Parallels Xen etc) but probably the best supported is Vmware. There is a free Vmware player that runs on Windows. Mac and Linux which can open the Vmware images linked below.
TinyERP (now OpenERP) http://www.vmware.com/appliances/directory/786