I had added "SMS With Molly" some weeks ago. It's ok, but limited... and folks can't respond to it.
So today I added the skill called Mail Box. It interfaces to Google Hangouts, which is what I use for texting on my iPad. It allows you to send email and SMS to folks on a contact list.
It seems buggy, and has more difficulty understanding what I say than other skills. But the concept is great.