I love keeping pesto made in the fridge at this time of year. Our local green grocers does large bunches of basil at a really good price at this time of the year. I make a big bunch of it up into pesto and then use it on tomatoes (which I like to keep out of the fridge so they are really tasty), fresh pasta with sautéed courgettes or with just to dress up shop bought hummus and lunchtime sandwiches.
If I have time I get the pestle and mortar out to make it as bruising the basil leaves in that gives it more flavour, but if not I simply chuck the basil in the blender with a couple of cloves of garlic and chop it find, then add about the same weight of grated Parmesan and toasted pine nuts, together with a good slug of olive oil. Blend again but leave a bit of texture, then jar it up with a layer of olive oil on top to preserve it.