If we were having a shower/gifts, I totally would have asked for our double Chariot and our carseat, which were pretty much the only big things we needed.
Those insanely cool highchairs (ah! name escapes me!) that convert into lovely grown up wooden chairs after being used for both infants and toddlers as they grow are super cool.
We use the heck out of our sheepskins and bouncy chair (so I can shower!), but they don't really wear out, so maybe you still have yours. Padraigs? Safe bath toys (like the natural rubber ducks from Rich Tree Frog)? We have one of the reversible BabySoy hoodies in the smaller size (0-6 mos, I think?), and dd literally wore it from birth (sleeves rolled up a bit!) until she was almost one, and then we got the next size up! They're great.
Have fun at your shower. Very cool that you're getting one with #3.