We did a Jungle Animals theme.
I have twin boys and we invited only our very close friends & their kids for their 1st birthday. It was more like a thank you to our friends for all their help and support.
The cake was a jungle with wild animals and so were all the table decorations. We had animals as window and room decorations.
Did small individual cakes for each of my twins, they dug in their fingers and had cake all over their faces --- great photo op!! We had a separate big theme cake for the guests. Lots of food and drinks.
We also did a game where we put about 8 items on a tray and let the birthday kid pick or touch one, thereby predicting his future career! Each item depicted a career focus (toy airplane for pilot, toy stethoscope for doctor, small calculator for accountant, dollar bill for businessman, paint brush for artist, etc)
We spent a lot of time & money on party favors ... they were more like 'thank-you-for-being-special-friends' gifts .... different items for all 50 guests, based on their age & individual interests, ranging anywhere from $15-80. They all also got chocolates with a customized wrapper .... I designed wrappers that had pics of both boys + all the info about weight, height on 1st birthday, and the story about their first year. All in all, it was the most memorable birthday, exciting time with our best friends. And I had a blast planning it for over 2 months!