With the introduction of Skype 1.4, which is currently in beta, you can have calls to your SkypeIn number forwarded while you are not online. For example, you could set it up where your SkypeIn number forwards calls to your cell phone if you are offline. This is very cool. The only downside I see is that forwarded calls still use your SkypeOut minutes. On the other hand, that is still super cheap telephony since anyone in the world with Skype can now reach you on your cellphone without costing them a thing.