I'm currently writing a D7 i18n book for Packt (hopefully out in March). I've written the chapters on the regular stuff: interface translation, node translation, field translation, blocks, views, menus, taxonomy, users, comments. I'm now working on the final chapter that has advanced or less common topics. So far, I have:
- Ecommerce (via Commerce module)
If there is a topic that you'd like covered, please leave a comment. I can't promise it will be included (page count is very short), but, if it's something of general interest, I will try!
Also, if there is an issue that you had or are having with D7 i18n that you want to make sure is included, feel free to leave a comment. For example, the Metatag module currently doesn't work with field-translated nodes so that will be mentioned along with the URL to the issue so people can track it. Perhaps you have experienced some pains or some a-ha moments that you'd like to share!