I am considering adding oysters and mussels to my vegetarian diet as a result of these two blog posts. I don't have Good Information about the nutritional problems that come from avoiding meat or the nutritional benefits of adding oysters and mussels, but it seems like a good way to hedge against deficiencies without spending too much research time, especially since I'm cutting down on eggs (Warning: unpleasant image of chicken having its beak clipped appears relatively high on that page).

That being said, I do consider this kind of thing to be "reconciling daily behaviours with abstract ethical beliefs" more than I consider it an effective form of altruism; it looks to me like poverty and the long-term future are much better places to invest Actual Altruistic Effort.