I've used some from Briarpress. I've also made use of characters in pi/dingbat fonts that are available from a number of sites like:
http://www.fontgarden.com/dingbats/dividers.html
http://www.dingbatdepot.com/
http://www.fontcubes.com/dingbat/popular
http://www.dafont.com/
and bitmap images from:
http://bibliodyssey.blogspot.com/200...ornaments.html
Also, there are a number of old type foundry specimen books at the Internet Archive like this one:
http://www.archive.org/details/booko...ecim00barnrich You have to use a bitmap image in the ebook when you use these but a simple screen capture, paste into Photoshop, and crop and make adjustments yields very usable ornaments.
I generally place small bitmaps, typically 4 color GIFs if B&W or 8 color if colorized, in my ebooks rather than deal with format specific vector images or embedding a custom font.