My newest app has just been published. My XLIFF Localization Helper lets you review translation resources directly on your Windows Phone 8 phone. If someone emails you a translation, you can open it up in the app and review the phrases and translations. It's currently free. The next version will allow you to make changes to the file and send it back with updates. The modify feature will probably have a low price to it. It registers itself for the XLF extension so you don't need multiple steps to open your file. Let me know how it works for you!
Note: The XLIFF standard is pretty extensive. Current functionality is limited to features used by Microsoft's Multilingual App Toolkit.
Link: XLIFF Localization Helper