Cheap voice calls is only a tiny part of it; about the only place I use them is to cheaply dial into hour-long W3C conference calls, where it's nice to be using a headset and where I'm frequently listening more than talking.
No, where Skype is *really* making a difference for me is in its instant messaging. Even when FP was smaller and we sat around a single table, we evaluated things like IRC for use as a company "backchannel" - somewhere you could put stuff without necessarily interrupting everyone. It never seemed to really catch on, and neither did Jabber (though we used Jabber throughout the Trutap project to bring our team and the Tappers in London together).
Somehow where these other tools didn't catch on, Skype seems to be working for us. We've quietly settled on it as the tool we use for IM within the company, and use it in quite a few different ways: as a general company-wide conference chat-room thatlets anyone post interesting links, ask about lunch plans, etc. (particularly useful when some of us are working from home, out of the office, or abroad); for problem-specific chat-rooms which tend to get formed when an issue of interest to a subset of the company gets discussed, and hang around nearly-indefinitely in some cases, become "project rooms"; and for individual, private chats.
What makes Skype so good for these? I can't quite put my finger on it, but I suspect:
- You can connect from practically anywhere - it seems to route around lots of port blockers nicely, and we have clients for just about every desktop platform (and some mobile ones);
- When you join a chat-room, you get all the messages you've missed. Really handy for catching up on old conversations;
- Few people I know outside of work are on it (as opposed to MSN, where I have a pile of old colleagues, friends, etc. - hopping online on MSN seems to be advertising myself as available for interruption, sometimes);
- It's really easy to start a new chat-room, there's no cost to diving off and talking privately;
- Being able to change the chat-room topic opens up all sorts of possibilities for levity - the room feels like "ours", and regularly changes title as the whim takes us;
- IRC-style "actions" (e.g. "/me doffs cap") similarly open up a bit more room for expression;
We make zero use of Skype for calls as a result of this: at FP our communal use of it is entirely based on instant messaging.
And the last place I'm using it is for family communications. Since hooking my mother to the interwebs last year, I've found myself rather enjoying being able to see her, or my sister, niece and nephew, hop online and video-chat with them. It's a very different sort of communication to voice chatting (you can't get away with distractedly doing other stuff mid-call, for one thing) and has augmented, rather than replaced, my use of regular mobile voice calls. I'm not video-calling instead of this, but as well as...