So how can you make sure that you're not writing a book with a main character named Bella the same year Twilight launches? Unfortunately, there's no full proof answer, but there is a handy tool to help.
First, you should check out Triona's handy post on baby names. There lot's of good info there to help narrow down your options.
Once you have your options selected, check out this baby name predictor tool which uses statistics to estimate how popular your name will be across the next 25 years.
For fun, I plotted me and my fellow blogmates to see what it had to say about us.
It looks like Stacy, Jennifer and Lauren have all peaked and are on the popularity decline. So if you write YA and want a name that is common among the peer set you're writing for, all three names should be avoided since it's less and less likely they will appear in pop culture. (Hint: look for a spike around the time your target audience would have been born.)
If you want an uncommon name, consider Stacy. Based on the chart, people born around 2000 are unlikely to have that name (which is a shame, cause it's awesome. :-P) And if you want something really unique, give Triona a try. In addition to being lovely, it didn't register as a name with any popularity spikes, meaning it's quite rare.
If you want even more nerdy name tools, here's a great article discussing how names can be used to predict someone's age (with the help of statistics, of course.)