Everything looks lovely! I'm very envious of the lettuces, especially.
Some ideas:
radishes - fast-growing, pretty, eat straight from the garden or stir-fry or chargrill.
courgettes - if you have the space :) you can train them up a framework. Lovely to pick tiny courgettes for grilling and stir fries.
coriander - love the leaves and, if you let them flower, lots of seeds :)
I got some courgette seeds the other week and then my sister said they grow on the ground. But I have done some googling based on your comment, maybe I will give it a go since I'm growing some mangetout peas and they need to climb. Thanks for your suggestions!