I bartered with my midwife for about $300 worth of sewing stuff: birth ball covers and privacy pants. They are both VERY easy to make. I made birth ball covers from the pattern at
www.bestdoulas.com and I made privacy pants like this:
www.geocities.com/examwear (actually, these are some that a friend's mother made based on my prototype). I'm now training with my midwife and haven't seen her barter a whole lot in the last year (she is now a single mom and really needs income more than anything else), but I do know that one client has made her a platform bed with drawers underneath for the waterbirth room at her birth center, and that she has offered to let mothers do secretarial work or painting for her. The problem I see with bartering services is that most of the time she doesn't keep very good track of it and the mothers end up not providing the service that she's agreed upon.
As a midwife, things I would barter for: someone to re-wire my house (I'd probably end up paying some for that!), organic produce, house cleaning service (not the mother herself b/c that would be weird for me, but if she had some connection, I'd use it!), furniture for my office, landscaping supplies or design, new windows for the house (again, I'd pay the difference), advertising work (I just had a doula client whose husband was a graphic artist, but I found out after they'd already paid

), picture framing...hmm...there are lots of things that I would be interested in trading for. It will really come down to what I need more at the time, though. For my first few clients this fall, I'm really going to need the money so that I can buy things I'll need for their births, so bartering won't be much of an option. I do plan to have a payment contract, and barterting agreements will be recorded on that contract so that they will need to be fulfilled just as the payment agreement would need to be fulfilled.