What is the smallest (installed size) ubuntu based distribution?
Try Ubuntu minimal ISO from here.
Choose the packages you want to install and you are done. You can try using LXDE or Openbox Desktop environment as they are not heavy on resources.
If you want just a simple Web browser and few cloud based services try an OS called xPUD.
xpud.org
8GB is not a small size. You can use Ubuntu with a 8GB hard disk. But If you are still looking for a more lightweight Ubuntu based distro check this out. I am not sure which ones among them are still active but I suggest those personally.
- Lubuntu which runs with LXDE desktop.
- Bodhi Linux which runs with Enlightenment window manager.
- CrunchBang++ Ben Young's continuation to Crunchbang Linux. Debian + Openbox
- BunsenLabs Linux Community continuation to Crunchbang Linux. Debian + Openbox
Remove /usr/share/doc or something like that. I've never used help files for graphical applications, so I've cleaned about 400MB of disc space. :) (I use Kubuntu 11.04)
I agree with Dejans' answer:
Try one of the many Lightweight Linux distribution, see list below: Make sure, that your hardware requirements are met, before deciding on one of the distros. I also suggest you to definitely buy "1GB of RAM" or maybe "2x1GB of RAM" on ebay for a small amount of money, so you can't go wrong with Lightweight Linux and also it is a huge improvement in your work flow!!
For your current 512MB RAM option, please see: List of Linux distributions that run from RAM - which shows you the required RAM specs.
Also antiX (see link below) seems to be a good/fair option for old/older computers, to be considered!
Alpine Linux - A security-oriented, lightweight Linux distribution based on uClibc and BusyBox. Mini download is 66 MB; base system (excluding kernel) is under 5 MB.
antiX - Lightweight version of its parent distribution MEPIS Linux, based on Debian testing. Core Install: 128 MB, Base approx 300 MB. Package Manager: Synaptic
BasicLinux - A very lightweight distribution capable of running on an Intel 386 and 3 MB of RAM
Bodhi Linux - A lightweight and minimalistic distribution, based on Ubuntu 12.04
CrunchBang Linux - A relatively large (771 MB) Debian based distribution designed primarily for speed and ease of use.
Damn Small Linux - Download 50 MB. Additional software available as "DSL Extensions" and using the Debian APT tool, which has to be installed. "Light enough to power a 486DX with 16 MB of RAM"
Feather Linux - Lightweight Linux Distribution derived from Knoppix. Now dormant.
Lubuntu - Lightweight in comparison to Ubuntu, it uses the LXDE desktop.
Nanolinux - 14 MB distribution based on Tiny Core Linux.
Peppermint Linux OS - Peppermint Linux OS based on Lubuntu
Porteus - It weighs in at under 300 MB, making it a lightweight contender, comes with the LXDE and KDE desktops
Puppy Linux - Lightweight relative to most other Linux distributions Download: 133MB. Package Manager: Synaptic (Lucid Puppy Ubuntu Compatible version)
Semplice Linux - lightweight, fast and simple, based on Debian Sid
SliTaz - 35 MB distribution; Package Manager is Tazpkg with its repository of packages
Tiny Core Linux - 12 MB distribution; Software repository: TCZ packages
Trisquel Mini - Lightweight version of Trisquel with LXDE
This one is pretty cool for a small hard drive http://www.ubuntu-mini-remix.org/