Today I was googling for an alternative of Teamviewer for Ubuntu and I had found it. It is Teamviewer itself.
Teamviewer can also be installed on Ubuntu, Linux Mint or other Debian based Linux distro. I have tested it on Debian Sid, Ubuntu 12.10 and Linux Mint 14.
How to install Teamviewer?:
First download the teamviewer*.deb file, for your arch:
* 32 bit:
$ wget www.teamviewer.com/download/teamviewer_linux.deb
* 64 bit:
$ wget www.teamviewer.com/download/teamviewer_linux_x64.deb
Next, install the deb file, like this:
$ sudo dpkg -i teamviewer*.deb