I was wondering if it's possible to install multiple distros all to one LVM (like say ubuntu, Fedora and openSUSE)??
yes yes it is. when you are installing your system, you should setup all the LVs that you need. After each install, be sure to backup the grub/menu.lst or grub.conf file as eat distro will overwrite it. At the end you will need to piece this back together to suite your needs. All the distros need to share the same /boot and need to not share anything else, including SWAP and / alternatively, you could have different /boot filesystems in different LVs and then make 1 first level /boot filesystem that no distro uses. Then in that one you can chainload the other /boot filesystems. when installing the distro you would need to choose to install grub to a partition instead of the whole disk. Then manually adjust the main boot filesystem for each new OS. That would allow you to have an un-modified distro running in each LV and you could use the standard update mechanisms and not worry that it will break your system. Alternatively, consider using KVM to virtualize the other distros you want to run. with newer KVMs you can pass PCI devices inclusing graphics cards and USB ports to the VM. There is a $99 USB VGA+USBport devices out there on google that works well for this.
