Useful links

InDesign

InDesignsecrets.com is your one-stop shop for all things InDesign.

Regular expression

InDesign GREP Help by Jongware

ePub

EPUBsecrets — created by David Blatner and Anne-Marie Concepcion, and hosted by Matthew Diener, ePUBsecrets.com is the world’s best resource for all things EPUB.

EPUB InDesign Scripts

EpubCheck — a tool to validate IDPF EPUB files

EPUB Validator (beta)

EPUB Straight to the Point book by Liz Castro

Pigs, Gourds, and Wikis — a blog by Liz Castro

Here are some links that might be useful for you to get you started with fixed-layout ePubs:

How to Create Fixed-Layout iBooks by R. Scot Johns

Field Guide to Fixed Layout for E-Books a free ebook on the ins and outs of Fixed Layout EPUB

EPUB 3 Fixed-Layout Documents

 ePubCrawler -- InDesign to Fixed Layout EPUB converter. (a tool for converting InDesign documents to fixed-layout ePub. It worked very well for me: I had to make only small adjustments to CSS styles).

Unicode

"On the Goodness of Unicode" by Tim Bray

"The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)" by Joel Spolksy

Unicode text and Unicode files in UltraEdit/UEStudio

XML

InDesign / Working with XML