On this page are a small selection of the images I have created for wikipedia. All these images (and in fact all images I've made for wikipedia or wikibooks are released under the GFDL and the creative commons share alike licence. The earlier images were made using the drawing tools of Microsoft Word If you are interested in creating images like this see Wikipedia:How to draw a diagram with Microsoft Word. The later ones (speed of light onwards) were made using Serif DrawPlus 7. I have since moved on to inkscape.
This is one of the images I created to illustrate the ripple tank article. There are more on the page.
Used in the fractional distillation article - I have a set of predrawn chemical apparatus that I use for this type of diagram. I can therefore knock this type of diagram out very quickly.