HL2:E1 is down to $15 on Steam--not sure how long it'll last, but I might be picking this one up.

On a side note, for the paintballers among us, I just installed the Digital Paintball Gold mod--I tried an early version a year to 18 months ago and it was pretty cool (although a bit short on players). It's now listed under Steam's "free stuff" and it's being hosted (and plugged, one would assume) on paintball and gaming sites alike, so hopefully the population will have increased somewhat.

(Whoops--Digital Paintball is for HL1, not HL2--looks like Steam's got an hour's worth of d/l....good thing I've got a couple hours worth of housework.)