I had a question of my own, and I googled for the answer. I thought it may be useful to post here.

Almost all cell carriers have an email to SMS interface. This could be used by friends/family in the US to send a text to your Jamaican cell phone.

For Lime it is: 876XXXXXXX@txt2lime.com. ( Use your phone number instead of "XXXXXXX". )
For Digicell it is: 1876XXXXXXX@digitextjm.com

Of course I found this using google, and I have not tested either method. If anyone can verify that would be awesome!

The reason this is important to us, is that it seems Lime has very cheap rates to call the US. My wife runs a business, and there are times her employees really need to talk to the boss. Instead of running up the higher US based phone international rates by them calling looking for us, we plan to just have people text us with a request to call in. That way she can also call back when it's convenient to her.