Here's my bets (maybe I'll corner pg one day and find out if I'm right):

1. Loopt (this is the only one I'm sure is on the list)

2. reddit (news.yc is rather overwhelming evidence)

I'm on to pure speculation at this point...but I'll take a stab:

3. Zenter (the only thing I think makes this possibly not as likely is that they sold so quickly...I think pg might like to shoot for something bigger and more world-changing this time around, since he already has plenty of money...maybe Weebly or Buxfer would be number three in that case, while Parakey probably gets disqualified for the similarly early exit)

But, I obviously can't speak for pg, and I'm just making stuff up based on limited knowledge. Take it as you will.