When designing your babysitting business cards, stay professional, but do think outside the box. Keep in mind that tiny paper cards aren't the way most people keep contacts--they're kept electronically for the most part. A hard-copy babysitting business card should be only a component of your contact package.
The other component should be a v-Card attached to your emails, as well as occasional blast emails to clients (maybe you're running a special, starting a day-camp, or simply giving tips of fun things to do after school or during the summer). All your emails should have your contact information in the closing.
A word of advice: Take a look at all the ideas you'd like to figure out how you want your business cards to look, but keep in mind that you can save a good amount of money by printing them yourself at Office Max, Office Depot or FedEx-Kinko's.
If you aren't confident with your design skills, it may be a better idea to purchase the idea you see online. However, every computer comes with software for designing business cards.
Zazzle.com's business cards section may be the only place you need to look. It offers tons of different looks and feels for reasonable prices.
eHow's site tells you exactly how to print free babysitting cards that still look professional.
Another idea is to go with an actual card that is larger than a business card. That way, instead of being hidden in a wallet, it may end up on the fridge or on a cork board with constant visibility.
Check out these announcements and imagine how easily they could be turned into babysitting business cards. With more space, you can add a picture, a few bullet points about yourself (college degree, years of experience, etc.), and make a more compelling design.
Bigger babysitting cards means bigger cost typically, so weigh the extra cost and determine whether it is worth it to you.
Another option is a photo card/business card. The focus would be a great picture, and the opportunity is to print off pre-designed cards for much cheaper than typical paper business cards or announcement cards.
Another cool idea for announcing your babysitting business and creating a keepable business card is the business card/post card. Vistaprint has fantastic products, and a customizable post card is a fun way to help your clients remember you.