How is your soil used? A book i have recommends growing things in it to break it up. I know that can be easier said than done with clay soil, but having dug in plenty of organic material last autumn I'll be filling in all the gaps in my border with annuals this year. On the plus side clay soil is supposed to be very fertile, and there are some plants that like it.
We're also cheating and putting in a raised bed for veggies.