I have some experience gaming online with Google Hangouts and Roll20 and have had some mixed experiences. Sometimes it's technology failures or complications, but sometimes things just don't seem to vibe as well when playing with a virtual tabletop. However, I've heard of and watched (on YouTube) some great online play.
I was hoping that some people who have had success (either long-term or one-shots) with virtual tabletops or Skype/Hangouts could share what they find makes things easier and more comfortable during play, from both a player and a gamemaster's perspective.