Previously I used Powerpoint to make figures for papers and wmf2eps to convert them to EPS format. Then I got to know another software called MetafileToEPSConverter, which does the same job in a nicer way. (This entire page is for myself to remember the name of this application. I have already forgotten that several times and took a long time to find it again.)
Most recently, I use inkscape. Inkscape has several good features that Powerpoint does not have and can save files as EPS files. As I wrote in here, with textext, Inkscape can handle latex equations.