From there I became interested in SVG, the open-source scalable vector graphics format which allows line drawings to be zoomed in or out without loss of quality. There's a good site VectorMagic.com which will allow you to convert a limited number of bitmap line drawings into SVG format without needing to install any software.
One of the best I've done is a scalable copy of the WWII "Keep Calm and Carry On" poster, which is in the public domain (no copyright) since Crown Copyright, at the time the post was made, expired after 50 years. Since it can be enlarged without loss of quality, it is suitable for reprinting as a poster or a t-shirt, in addition to being used as an icon. I've placed it on Wikimedia Commons and you can download it perfectly legally from:
I've also been looking at games to play on my Asus Eee 901 netbook running Ubuntu-Eee Linux. Last night I perfected my install of classic Quake using ezQuake after I dug out my original v1.01 DOS Quake CD (which, yes, was covered in dust) to obtain the pak1 file. I'd forgotten just what a superb, fast-paced, involving game this is. In particular I'd forgotten how much fun it was exploring the maps to find the various keys needed to progress through locked doors. Since the game runs so fast on modern hardware, you can run from one end of the map to the other without any lagginess, and you never get bored travelling around.
Of course, this meant I needed a classic Quake icon. Ubuntu-Eee comes with a dark background, so the original Quake icon didn't stand out. I added a yellow-ish border to it, and it stands out much better. Available as an SVG here.
Update: Being colour blind, it's possible I've got the background red colour wrong on the Keep Calm poster. If a fully colour-sighted person could give me a corrected HTML RGB code, I'd be very grateful. Currently it is: #F50401