I have a second number from Anveo.com that I can forward to any number in the world. They have voice mail and smart call flow routing so you can do things like

I have a second number from Anveo.com that I can forward to any number in the world. They have voice mail and smart call flow routing so you can do things like forward unanswered calls to another number, set up a mini IVR system (i.e. "Press '1' to call me on my mobile", "Press '2' to call my mom", etc.). They do SMS forwarding for some countries, as well as web based SMS. They also have a nice service that lets you purchase a number in a foreign country and forward it to your own number. My relatives live overseas so I bought a local number in their country that they can use to call me for free. it only costs me a few dollars/month. None of these features are unique to Anveo, but I've been using them for a few years and have been quite happy with the service.