Currently Being ModeratedJan 21, 2013 5:04 AM (in response to Leawb)
You need to change the addresses to which iMessages are received on each device. Read http://support.apple.com/kb/HT3529 for more information.
Currently Being ModeratedJan 21, 2013 6:31 AM (in response to Leawb)
Use different email addresses - gmail - that you just use for FaceTime/iMessage.
Using FaceTime http://support.apple.com/kb/ht4319
Troubleshooting FaceTime http://support.apple.com/kb/TS3367
The Complete Guide to FaceTime + iMessage: Setup, Use, and Troubleshooting
Troubleshooting FaceTime and iMessage activation
Using FaceTime and iMessage behind a firewall
iOS: About Messages
Set up iMessage
Setting Up Multiple iOS Devices for iMessage and Facetime
FaceTime and iMessage not accepting Apple ID password
Unable to use FaceTime and iMessage with my apple ID
For non-Apple devices, check out the TextFree app https://itunes.apple.com/us/app/text-free-textfree-sms-real/id399355755?mt=8