I have been thinking about a third a lot lately. DS has been a much more cry-y baby than DD was, and for a while I was thinking maybe we would stop at 2. But we have always planned to have more than 2- in fact, the vehicle that we bought when I was pg with my 2nd was bought specifically because it would fit more 3-4 kids in the back.
At this point, we've pretty much decided that we will have a third at some point- we're just waiting for DS to be past the super clingy toddler stage (and DH doesn't know it, but I'm also waiting until I can get into a benefited position where I work, since DH's work has lost their good health insurance and we now have only crisis coverage).
I'll be 30 this fall, so I'm okay with putting off trying for a third until DS is around 2 or 2.5 (he's only 13 months now).
I'm one of 2, and I always wanted another sibling, and often felt kinda lonely when my older sister didn't want to play with me. Both my DH and my XH were one of 3 kids. My dad is also one of 3, and he has tried to make me vow to have a 4th if we have a 3rd (he feels like being the middle child is what made my uncle grow up to have such a rough life).