So, do most of you do this? And if so, what do you do with the beer? I feel so wasteful just dumping it down the drain, but it's not especially tasty...
A 1L starter I'll pitch at 18-24 hours and pitch the whole thing into the wort. When I make a 2L or larger starter, however, I let it ferment all the way out, cool it in the fridge for a day or two, and decant the starter wort.
How I do it depends on several factors:
How much time I have before brew day
How much yeast I need
How delicate the flavor of the beer will be
So for a light bodied, clean lager I'll do a big starter several days in advance and pitch only the yeast. For most ales I'll make a smaller starter the night before and pitch the whole thing.
I don't make less than 1.5L starters so I always decant the liquid. I just pour it down the drain. It doesn't taste great so I don't want it in my beer and I don't really want to drink it.
I remember Chris White from White labs saying on the Brewingnetwork 2000ml or under you can pitch the whole thing. I have done this before and have not noticed any off flavores but my regular routine is the same as Chads.