Insight is a very good debugger based on gdb. I prefer it over ddd or kdbg as I find it clearer and easier to use. Moreover, this debugger is also the one used in the book Assembly language Step by Step, for Linux. However, Insight has been removed from Debian packages already more than a year ago.
But, thanks to SevenMachines, a PPA repository is available to install it on Linux Mint (works also on Ubuntu and Ubuntu-based Linux distributions).
To add the repository to your apt sources, add the following lines to the /etc/apt/sources.list file:
deb http://ppa.launchpad.net/sevenmachines/dev/ubuntu natty main deb-src http://ppa.launchpad.net/sevenmachines/dev/ubuntu natty main
and update your apt sources:
sudo apt-get update
Then you can install insight:
sudo apt-get install insight
And now you are ready to use Insight as your debugger.
If you don't trust this PPA repository, you can also try it to install it from the sources (http://sources.redhat.com/insight/), but doesn't seem to very simple to install it. I wasn't able to build it on my Linux Mint 12.