Playing D&D and other games online isn't nearly as difficult or intimidating as I expected it to be before I gave it a try. It turns out that it's actually really easy to do. Technically, anyway, and there are a lot of free services out there to facilitate it.
I've spent most of my time using Google Plus hangouts, though I've also used Skype, and for the most part the audio and video quality has been good on both.
DMing online isn't really all that different from DMing at a table, except that there is a big screen between you, as opposed to a little DM screen. Without using an extra service, there isn't a good way to roll in the open, which means that you have to trust your players to honestly report their rolls. Or you can use one of the many online dice roller programs. You also lose out on a certain level of goofing off/pregame chatting, though I've noticed that the longer a core group plays together, the more this picks back up. One thing that doesn't is the physicality of sitting around a table. There are times as a DM when I'll use physical action to help me show something that's happening in the game. That's a lot harder to do when you're confined to the view of a webcam. It also takes some practice to learn not to talk over each other. This is an instance where having a "caller" might actually be pretty useful.
I've played mostly old school games, rather than newer more tactical games, and since they require more imagination than gameboard and minis, describing the rooms or monsters as I would do with a group around a table works pretty much exactly the same. Sometimes, for a really complicated situation I'll sketch something on a piece of paper and hold it up to the camera for the PCs to look at. PC map makers tend to do the same thing, for me to make sure they didn't go completely off the rails.
While it does lack a certain something, gaming on G+ is really what got me rolling dice again, more than I have since high school and college. Plus it's let me play with people literally across the world, crazy, inventive, imaginative players and DMs who I never would have gotten to roll with otherwise.
If you haven't had a chance to play online, and you're itching to get back to gaming, give it a try. And if you're looking for a place to start, check out the Hangout RPG community on G+.
This is post #28 in the 30 Days of Gamemastering Challenge.