Used VMware Server (Linux) for Linux?
You will need to register on developer's site to receive free serial numbers.
Developer’s Description
By VMware
VMware Server is a free virtualization product for Windows and Linux servers with enterprise-class support and Virtual Center management. It enables companies to partition a physical server into multiple virtual machines and to start experiencing the benefits of virtualization. With Virtual Center add-on, users can efficiently provision, monitor and manage their IT infrastructure.
Explore More

Lightput for Ubuntu (32-bit)
Free
Universal File Mover for Linux
Free
ViewVC for Linux
Free
Edubuntu for Linux (64-bit)
Free
Zentyal Linux
FreeLightScribe Simple Labeler (Linux)
Free
VirtualBox for Linux (64-bit)
Free
Xfe for Linux
Free
Anjuta Extras for Linux
FreeVMware Player for Linux
Free
UNetbootin for Ubuntu (32-bit)
Free
Edubuntu for Linux (32-bit)
Free