I've fallen in love with
CalSmart Ice Cream by Breyers. It has great flavor, especially the vanilla (with vanilla bean specks!), quite good texture, and because it uses Splenda, only 70 calories for an entire half-cup serving! It's not cheap, but my local grocery store puts it on sale on a regular basis, and I stock up.

Add a little Hershey's Lite Syrup and you've got a great sundae as well.
I've also been enjoying
Health Smart bars by Blue Bunny, in the lemon/lime/orange shebert flavor. Blue Bunny isn't actually available in my regular stores (or anywhere on the West Coast), so I must confess that I found these bars at the Grocery Outlet - but they're really great! A nice big bar for 70 calories, again made with Splenda, and really yummy.