Here's a place for us to post our favorite things. 

My #1 all time favorite is my baby monitor, I had the angelcare monitor that has a breathing detector. (the now have one that has video when I got mine they didn't sell that one)(I loved it so much I wrote a review on it here)  

Registry Must haves: 

- Boppy

- different types of bottles

- different types of sippy cups

- diapers 

Items I could live with out

- Bumbo

- Bumbo tray

- the million and 1 blankets I registered for 

- I also registered for bath shampoo/body wash, i dont remember how much I registered for but I STILL have some from my baby shower and alexis is almost 2!

OMG, the breathing detector is so cool!  I can't even count how many times I've babysat kids and wandered into their nursery while they were sleeping to make sure they were still breathing.

Ditto on the breathing detector! Sometimes I can't tell if DH is breathing! He's such a peaceful sleeper.
I did start my registry but nothing sticks out as a must have since it seems ALL these things are must haves.
Question: do I still need a boppy if I already have my brestfriend? I received a hand-me-down from a friend.

I could not live without my sleepy or moby wrap early on, and then my ergo. Absolute must haves. And a breast pump and nursing tanks. I didn't register for diapers since we cloth diapered for a while, but also because I didn't know what type I would like and what sizes - my kid went from newborn to size three pretty quickly so I am glad I didn't have a stockpile since we would have had loads left over. I recommend a video monitor for sure - its helped a lot now that my dd is older and she will cry a bit during the night and I can look at the monitor and see that she is still laying down and sleeping (therefore I do not need to get out of bed!) without going in and risking waking her up. I also LOVED our arms reach co-sleeper.

I didn't use a boppy for nursing a ton but I used it later on for sitting up and playing on the floor - I would get one for that since they aren't super expensive.

Thanks for the boppy tip KristinKay and welcome!

We also have the AngelCare monitor!  Since G is 9 months I have turned the sensor pad off but left it under the crib for when he has a stuffy nose.  Love it :)

My must haves / what I used the most:
Swing - we have the Fisher Price Snugabunny that plugs in, so sad when I packed it away!
Diaper Champ - like the diaper genie but uses regular trash bags
Bottle Warmer - we recieved the First Year Deluxe Bottle Warmer, it's around $35 a BRU and I hate that thing!  I gave it to my mom and got a Munckin one for $20 at Target.
Wipes!!!!  You will go through so many wipes!!!!

We didn't really use the Boppy at all - I use it now as a pillow for me in his room.

Tips -
Don't go overboard on Newborn diapers and even size 1 diapers...size 3 diapers are good to put a lot on since they stay in those for a while.
Diaper creams - we are still on the same tube of Destin 9 months later and there is still more then half in there