There are three lightweight distros I have been playing around with in Virtualbox. I have all three set up with only 500 MB of ram which allow me to have all three runnig in the screencast below. So here is the quick rundowm of the lightweight distros.
This is one of my favorite go to light distros. A pet peeve of mine is when folks recommend xcfe as a light weight alternative when Peppermint is available.
Peppermint is based on the LXDE environment with minimal desktop apps installed. You will find no Gimp or Libre Office in this distro. In the age of dial up maybe distros packed with app after app made sense, but I think Peppermint is on to something with their "Just the OS Mam" approach.
But being minimal is only half the story, they consider themselves a hybrid os, between Chome OS and full Linux distro. They accomplish this with their Ice framework that treats web based apps and websites like any other program on the computer.
I love their edge snapping and am excited that Linux Mint 17 MATE with offer similar capabilities. In Mint 16 MATE I am always finding myself dragging a window past the edge in some sort of limbo.
Now if you thought Peppermint was minimal, you will love Bodhi. Upon boot you are given three options; minimal, modern, and desktop. I was looking at Bodhi as a Chrome OS like distro so I chose minimal. It should be pointed out that Bodhi is a popular distro to install on Chromebooks.
Well I did say minimal. There was just the background and nothing else. Clicking on the background pops up a menu with a very limited selection of apps. I installed Chrome and a menu button and that is it.
Bodhi while minimal felt very modern. I really liked their menu - black and sleek - with full control of the distro. Functionality wise it reminded me of the Mint Menu, menu allowing one full control of the distro.
If its good enough for Snowden, its good enough for me. While this distro is light on resources, it is not light on security features. One nice feature is it allows you to boot into Tails with an XP interface. Those (humans and bots alike) that see you on the net see an XP machine.
I have never attempted to install Tor so it was cool being able to choose which country I would surf the web from. Another feature I really liked was encrypting ones clipboard.
All in all these are all features someone could add to most Linux distros but its nice having it in one package. You can go to any computer, boot up Tails, and when you are done you have not left a trace.
Right now these are my favorite light distros. While they may be too light for running as your primary distro, they are certainly light enough to run in Virtualbox for specific purposes.