When you have a child with Down syndrome, there are quite a few developmental things that are pretty cool to have, and some stuff to be aware of. Anything we can do to help our little one's brain's and body's grow is good stuff!
There is also a list on the Down Syndrome Pregnancy Blog that has additional suggestions - be sure to read the comments!
Here are some of my favorites - things I used and loved, and things I wish I had:
Videos
Our little people are very visual learners!
Love and Learning apparently helps them learn to read the sight words - it is pricey, and it features kids with DS. Lots of families have been very successful with the program.
http://www.loveandlearning.com/home.shtml
Signing Time is a fun, fun, fun way for you and your child to learn to sign - most kids can generally sign before they can speak, so signing is a great bridge language for them. If there were one thing on this list (other than the nose fredia which I'll get to in a bit) it would be this.
http://www.signingtime.com/
Stuff
I never had one of these slings, but it apparently is built to support their little legs better than a typical baby carrier that spreads their already loose ligaments even more:
http://www.babyktan.com/
How cute are these for chilly times at therapy?
http://www.babylegs.net/
Now, my baby rolls all over the place now, but I still start her off at the top of the crib with this wedge underneath her. Our kids tend to get reflux quite a bit, and this helps elevate them. I put UNDER the mattress.
http://www.target.com/Safe-Lift-Deluxe-Universal-Wedge/dp/B00067AUP2
Toys
One of my favorite first toys - this one is so easy to spin and get moving at such a early age - Violette loved it!
http://www.amazon.com/LeapFrog-Spin-Sing-Alphabet-Zoo/dp/B000NRX5XE/ref=sr_1_1?ie=UTF8&qid=1242008836&sr=8-1
Big fan of the Fridge DJ - make sure you get this one and not the Learn and Groove Radio! It plays really cute music and plays a lot of alphabet and number songs
http://www.amazon.com/LeapFrog-Fridge-Magnetic-Learning-Radio/dp/B000EULX8E
Because our kids are so cute, why not give them a way to look at them self all the time?
http://www.geniusbabies.com/lamfirmiraww.html
Tummy time, tummy time, tummy time. I was told that tummy time was the best way to get my baby strong all across her body. This little toy really helped get that tummy, and neck, strong!
http://www.geniusbabies.com/spin---explore-garden-gym---lamaze.html
Melissa and Doug make THE BEST toys for any kids, but I think there are so many that they have that are helpful with a lot of the things that our kids have deficits in. Love some of their simple puzzles (check out the jumbo knob puzzles)
http://www.melissaanddoug.com/shop.phtml
Congestion and Reflux
Our kids tend to get a lot of yucky congestion - I loved this to help that out:
http://www.drugstore.com/qxp148010_333181_sespider/simply_saline/sterile_saline_nasal_mist_baby.htm
Speaking of yucky, this product isn't for the weak of heart, but dang, does it work. After you see your LO suffer for a while, you'll want one of these. Trust me.
http://www.nosefrida.com/
Books
First, don't read anything that wasn't published in the last few years. There is a lot of outdated information out there, and some of might wrongly scare you because they are based on old thinking.
I Can. Can You? Is such a cute little board book featuring kids with Down syndrome. My Child really like it, and the one that I have listed underneath it!
http://www.amazon.com/Can-You-Marjorie-W-Pitzer/dp/1890627577/ref=sr_1_1?ie=UTF8&s=books&qid=1242009472&sr=8-1
All of the Woodbine books are really helpful. Don't be overwhelmed by all of the information in them - I just pull them out every so often to see what suggestions they have for where I think my baby is at any given time.
http://www.woodbinehouse.com/Down-Syndrome.29.0.0.2.htm
I love these little books too!
http://www.woodbinehouse.com/main.asp_Q_product_id_E_978-1-60613-000-1_A_.asp
Let me know if you have any good things that I've left out.