SMS Polls and stuff?
I wanted to do something similar and used Poll Everywhere
There are several different types of SMS options, Polls or open ended questions (Live Text Wall).
Once you setup the poll you download a PowerPoint/Keynote file that contains a template and instructions on how to integrate LIVE auto updating Poll results into a PowerPoint. Once this is setup you then import that PowerPoint into EasyWorship just like any other PowerPoint. It works really great!
I first saw it used over a year ago at an ERP software conference in which the speaker polled the audience during the talk. He then used the results to dynamically change this talk to cover topics of more interest to the audience.
At our church our Youth Pastor was preaching in place of our pastor one week and wanted to get some direct live feedback from people during the service in regards to an open question. At first he was thinking ushers with mics, so we augmented the mics with the Live SMS wall. Got way more responses to the Live SMS Wall then just the mics. There was about 180 in attendance that morning and we rec'd @ 25 SMS responses.
For up to 30 responses per Poll it's free once you register.
You can use free polls to gauge how many people would respond... you get close to 30, then discuss with church leadership on usage and consideration to purchase a subscription.
If you need to moderate (approve a SMS text before it displays, you have to pay).