I have played World of Warcraft (intermittently) since January 2005, and was an early adopter of Gatherer. As the addon became more detailed and impressive, I found that there was a bit of 'information overload' happening with the map tracking. It occurred to me that the problem is that the icons used to represent the various plants and ores were overly complex. Many complex icons on screen can reduce the effectiveness of what you are aiming to present. Having identified what I perceived as the problem, I endeavoured to find a simple solution. Now originally I thought - well, use letters like chemical formulae for the nodes. But how to differentiate plants and ores? Use different fonts. This worked up to a point, but with TBC came all these herbs starting with F and N, and again complexity was beginning to creep in. Not long after TBC I took a hiatus for 3 years - I skipped all of Wrath and the first year of Cataclysm. But I've resubbed, and Gatherer is still working, and I have new icons to boot.
I went with a simple idea - dots for ores, squares for herbs. The colour of the dot is (mostly) representative of the item being collected. I have also added in the Un'Goro crystals and soil, Sithilyst and differentiate rich and regular nodes where possible. There's not a large number of ores to mine, so I didn't see the need for further splitting them between Azeroth, Northrend, Outland and Cataclysm. With herbs there are a lot so I took to the following scheme: a vertical divide indicates a vanilla WoW herb. A diagonal divide is an outland herb. A checker (grid) is Northrend, and a horizontal divide is Cataclysm.
Below are some screen shots of the icons in the game.
So, if you like the look of those icons, then you can grab the zipfile here : http://www.bluestar.com.au/wow/GatherIcons.zip Just extract them into your Gatherer folder. They're the icons plus two lua files that I had to edit to show the Cataclysm nodes and un'goro stuff.