Pumpkin Seeds, Sunflower Seeds, Walnuts, Almonds
I just tried pumpkin seeds for the first time a few weeks ago. Those things take like potato chips, and they're awesome for your prostate. The omega 6:3 is a little out of kilter (~14:1,) but very few foods have a good omega 3 content.
The good news is that they're high in fiber and in healthy fats (omega 6s, but still healthy.) So they'll help to keep you full even with smaller servings. And oh yeah, Pumpkin seeds have about 11g protein per 1/4 cup, sunflower seeds have 9g of protein, and I think Almonds and Walnuts are each a little lower (7g, 5g) respectively.