It was actually a little program I bought for $10 called the logo creator. You can pull images in and add words, quotes, siggies, etc.
I also have a great site if anyone wants to make their own siggie! I have another where you can make it sparkly, then yet another to bring them together. Alot of times ppl will just make a siggie though...adding glitter can get complicated and it makes the file larger.
Here's the site to make cool signatures/banners:
http://cooltext.com/Default.aspx
KD