We’ve seen time and time again how certain toys will blow up for one season (Furby, Tickle-Me-Elmo, Cabbage Patch), while others will continue to sell year after year. Today, we’ll look at a few examples from 2009 — though of course there are hundreds more.

First is Leapster, an educational handheld game console that teaches kids the alphabet, phonics and basic math (among other things). First released in 2003, there’s been a recent spike in demand for Leapster 2, released last year. Here’s a 60-day total sales trend for “Leapster”:

Next is a classic: Lego. Dating back to the 1930s, the little building blocks are a big-time seller all year round… but rarely to the scale that the holidays provide. Here’s a 60-day sales trend for “Lego” (which, last Sunday, totalled more than $1.5 million in eBay.com sales!):

And finally, here’s this year’s phenomenon: Zhu Zhu Pets. You may have read about them already — robotic hamsters! — but if you’ve yet to believe the hype, check out this 60-day trend for “zhu zhu pet”:

It’s a prosperous venture, this toy racket. Here’s to guessing what next year’s craze will be!