First of all, take advantage of modern technology. Face Time and Skype. It only takes a bit of time for someone not directly involved in the ceremony to set up a lap top or iPad to focus on the happy couple throughout the ceremony. That way they can be ‘live’ at the wedding. This worked great when my brother Tim and his new husband Luis got married last year in Canada. Luis’s family all live in Costa Rico, so we had them on Face Time during and after the ceremony. Tim and Luis made mention of them watching during the ceremony and spent time chatting with each of them after. We even had our Canadian family spend time saying hello and congratulating the Costa Rico family. When they talk about Luis’ family, they always mention that they were ‘at’ their wedding, and I know they felt very much included.
You can also video your wedding and send over the file after the wedding. While this can be done expertly by a videographer, not everyone has the money. There is nothing wrong with setting up a laptop much the same way as above to video the ceremony.
You can have long distance guests do a reading over the phone/facetime and mic it for guests to hear. You can have them email greetings which can be read at the reception. You may also consider having a poster board with pics of immediate family not able to attend along with their best wishes.
These suggestions are not perfect but your distance guests can feel more included.