Sorry to be off the radar, didn't mean to ignore doula questions.
I had a birth/post-natal doula and would really recommend both types of service. We weren't sure that we wanted her for the birth at first (DH wondered "what will she DO?") but she said that if she was free and I called her when I went into labour, that she would come. That's exactly what we did!
She came to the house about 5pm (contractions started at 5am) by which point I was having serious pains about every 10 minutes or less. She gave DH directions (take dogs for walk, eat dinner, etc) and helped me get through contractions. I had a Tens, but was having increasingly small amount of relief between contractions, so really struggled with recovery.
About 8pm we called hospital (she told me what to say!) and we went in. She sat in back of car with me (I was on all fours facing boot) and went into hospital with me while DH parked. Took us ages to get to Labour Ward! But by the time we got there, DH was there and they got us straight to a room.
Her most valuable role was support. She didn't "do" anything in particular, and certainly wasn't in the way. But I would look to her for support when asking questions of M/W or Dr and knew that she was there should I need her to back me up. She only offered opinions if asked. She held my hand and did a little hypno with me as well.
I think DH found her even more helpful than I did at times, b/c there were stages where they both had to leave the room while various things happened, and I think DH would have panicked without her to reassure him.
When things went wrong (placental abruption) and we went into theatre, I was really glad she was there (although she wasn't in theatre). I think DH was seriously worried and she reassured him again that this was the only course of action.
Even though I didn't have the natural birth I had intended, the doula was almost more useful in the kind of experience I did have. Or at least that's how I felt. I never panicked or felt out of control, despite the dramatic events. I put a lot of this down to her presence.
Post-natally, she was AMAZING. She brought freshly-baked bread every morning, cooked us fantastic meals (lunch and dinner) made sure I ate, did every scrap of laundry, made sure I slept and again gave DH stuff to do. I can't recommend this enough - I have no family in the country, so I knew I'd need help. After a CS, too, you need so much more looking after. And her kind of non-judgemental, neutral help was so valuable.
OK, sorry for the novel, but I could seriously go on and on about her. Get thee to a doula!