Actually Dub, I've been looking into this myself and I don't know if you've already check this out, but there are some options in the market that allow you to text over wifi and 3g. You might just search around under different topics dealing with your subject, such as..."texting over wifi"...or something along those lines.
Also you can text via email to a phone, but keep in mind that there's a pritty low limit on the file size you can send, atleast that's the problem I was having.....If you want to try it though, just attach the pic to the email like usual and try to send it, maybe figure out the Max size MMS, that the other person can receive.