As far as "Back to My Mac" is concerned, Apple presents it as a .Mac-only enhancement. Melvin Rivera pointed us to his blog post showing how to use Back to My Mac with iChat. This technique isn't for the faint of heart. It involves editing system preferences, modifying AppleScript, and causing your computer to always stay awake. Other than that, it's a great way to get around the Back to My Mac limitations and use your computer remotely.