Recently I wanted to order something that would include a company logo imprinted on the side. I had no trouble creating the logo, but the company wanted it in EPS format--something that few programs outside of Photoshop can create. (Freeware favorite Paint.NET can't do it; neither can GIMP.)
Fortunately, I found online-ConVert.com, a free site that can convert any image file to just about any format you need (including, thankfully, EPS).
All you do is select your file, choose any extra settings you may want (like sharpen or convert to monochrome), and then click Convert file. In just a few moments, the site uploads your file, converts it, and gives you a download that's ready to save to your hard drive.
You can also enter an e-mail address if you want to share the converted file with someone else or retrieve it later--but that's optional.
The site handles more than just images: it can convert audio files, documents, e-books, and videos. It also has a "hash converter" that will turn any snippet of text into an encrypted hash of your choice.
This is a great little tool, one I highly recommend bookmarking.