Gmail Labs, Google’s proving ground for new Gmail features, is piling on new stuff at such a dizzying pace that it’s hard to keep track of everything. Some, like the Breathalyzer-like Mail Googles, are enough to make you wonder whether that Google policy of letting engineers devote 20 percent of their time to personal projects is such a good idea after all. Not so, I’m happy to report with tonight’s new feature. Gmail now offers Tasks–aka a to-do list–and they’re such an obvious feature for the service’s bag of tricks that I was momentarily surprised when it dawned on me that it didn’t already do them.