My communications needs are complicated because I am on the road so much; In a typical month, I use a combination of e-mail, instant messaging, land lines, Blackberry, Skype account, SkypeIn number, and Iridium satellite phone to stay connected to the world. I may have found a service that will simplify everything. A few minutes ago, I signed up for a free GrandCentral account (beta), which gives me a single phone number that rings all my phones at once. In addition to offering simultaneous ringing, GrandCentral also offers customized greetings, call screening, call recording, phone transfer, SPAM/marketeer detection/elimination, ring sharing, voicemail sharing, and more -- and all of the features can be selectively activated by call group (keyed off of incoming Caller ID), so I can allow friends to get through immediately while screening those calling from unknown numbers.
While I'm on the road, I should be able to add additional numbers to ring as well, although I will have to wait until international support is added.