Definitely worth devling around in the labs. There are more useful labs items than in the dotTech list (imho). Things that ought to be enabled by default.
I'm late to the party on this one, but I've recently been trying out the Greasemonkey scripts for Gmail. Plenty don't work with the current Gmail but there are some handy scrips that fill the gaps the labs don't fill - though, I suspect, they'll find their way into the labs eventually.