A helpful reader noticed a new setting in Gmail that's popped up since the Undo Send lab appeared in Gmail. You can now change your undo buffer period to five or 20 seconds from the default 10-second wait.
andreasr2d2 provides this tip, having discovered it while hunting around in his Gmail Labs section. You'll need to enable Undo Send in your own Labs to see the setting appear in your General section, but it should come up soon after. The standard 10 seconds is probably fine for most, as one usually knows right away when an oopsie email is going out. But if that 10 seconds seems ghastly long, or not long enough to really think over what you just sent, you've now got two other options.
Got your own never-before-seen Gmail setting, or another tip to share? Tell us in the comments.