CONGRATULATIONS! I think it's great that you wanted to do something special to surprise your husband. A baby is great news and a great surprise, even when it's planned for. Since you've already told him I assume the rest of us are sharing ideas for family or other people who may want ideas.
My husband and I had been trying for 11 months. When I finally found out I was pregnant, I think he had almost forgot. It was 6 days before Christmas. Even though I wanted to run upstairs and tell him, I thought that I would never have a better opportunity for the best Christmas gift ever. We traditionally opened one gift on Christmas-eve. I bought cute little Swarofski crystal baby booties and put them in a box. I put a hand written note on the top that said, "Oh Boy (or Girl)! Ready or not, here we go". He was completely surprised and delighted. Then I had bought Precious Memories figurines for the grandparents. We had them open them last the next morning, Christmas Day. My husband loved being in on surprising our parents just as he was surprised. The screaming and tears of joy was "priceless". Keeping that secret for 6 days was incredibly difficult and precious at the same time. However, it was well worth it. I talked to my "little baby" as if he (now 5 years old) was helping me with the surprise. He ended up being the only baby we could have so I'm especially glad that he was announced in a way that is as special as he turned out to be for us...but then again, all babies are special and a miracle. They all deserve huge "welcome parties" whatever that might be. Again, Congratulations and Enjoy!