I gotta go with porites, too. I've got a whole rock covered with the stuff that started from a quarter-sized patch on a piece of liverock from my lfs. BTW, that link wouldn't work until I dropped the final / -
http://www.hawaii.edu/HIMB/Gallery/Porites.jpg
Here's a link to an alveopora picture for comparison:
http://www.melevsreef.com/pics/0804/alveopora_081804.jpg
Ok, that's not a picture of branching alveopora but I couldn't resist using Marc's picture. Dean, do you have any better pictures we could use to compare? And Tremelle, if you have a clearer picture so we can count the fringes on a polyp, it would make identification easier.
[Hey Marc, two pictures from Melevs Reef were in the top 10 Google image search results for "alveopora"; you're famous!]