A few more since server software was brought up -
Virtualization
PC Virtualization -
VirtualBox (Open Source Edition, the other one is only for personal and evaluation use! -
http://www.virtualbox.org/ )
Virtual PC (Microsoft -
http://www.microsoft.com/windows/virtual-pc/ )
Server Virtualization
VMWare Server (VMWare -
http://www.vmware.com/products/server/ )
VMWare ESXi (VMWare -
http://www.vmware.com/products/esxi/ Virtual Server (Microsoft -
http://www.microsoft.com/windowsserversystem/virtualserver/ )
Xen (Open Source project -
http://www.xen.org/ )
XenServer (Citrix -
http://www.citrix.com/English/ps2/products/feature.asp?contentID=1686939 )
Hyper-V Server 2008 (Microsoft -
http://www.microsoft.com/hyper-v-server/en/us/default.aspx?pf=true )
Note all the above are free hypervisors with the noted restrictions. The differentiation between PC and Server may serve as a misnomer, as all of the above support both server and desktop OS's and will run on either host. The biggest difference is two-fold. First and foremost the "PC" solutions run on top of an OS instead of installing "bare metal" or before the OS. This has several implications such as fewer concurrent machines, but it also means (in many cases) a smaller file and broader driver support. Some of the "Server" versions also run this way, but by and large, they are bare metal" software that requires to you install it before the Server OS you would want on it. Another distinction is that Servers are, by definition, purpose built; therefore many do not have requirements for a broad range of software (such as graphic related software). Due to this purpose driven design, many of the "Server" products do not support or take advantage of good display cards.
My personal recommendations based on what I have worked with is VirtualBox for general purpose and testing use and for running Server specific software, Citrix XenServer. It is a tough call, because VMWare is the king in the field with Microsoft an close second up and comer. However, both have very limited management capabilities - a point where XenServer excels (in the freeware space). As an added bonus, XenServer and Hyper-V can both be managed from the Citrix management console (and I believe Microsoft's console as well, but I am not certain). ESXi has VERY limited management. That said, if it is just a single server or two that are being managed (physical servers I am talking about here, not virtual ones), the ESXi is a VERY STRONG CONTENDER. The biggest advantages to the ESXi option are 1) Guaranteed compatibility with other Hypervisors (they may require conversion, but everyone supports converting from
VMWare's proprietary format*) and 2) there is a large "Virtual Appliance" showcase where you can download re-designed systems both for free and for cost. Some of these can be very useful such as pre-configured Gateway Servers, IDS/IPS servers, etc.
* Formats are becoming less important and OVF has become a standard format for transportability of Virtual Machines. This is a new standard, however, and not all companies comply with it fully as of this writing.
As for other areas, I suggest the PDF field include two from Sourceforge:
PDF Split and Merge (
http://sourceforge.net/projects/pdfsam/ )
PDFCreator (
http://sourceforge.net/projects/pdfcreator/ )
Both are GPL licensed.
Hope that helps add another new dimention to the list
