The best seeds to grow for swapping by a country mile are French beans - I'm growing them anyway both to eat the pods and to dry the beans; and they come true without any faffing about trying to keep them away from any other varieties just in case they cross pollinate.
Peas are also brilliant to save seeds from as they grow true too.
So to collect seeds for growing next year, or to swap, all I need to do in each case is leave a few pods (or beans) on the plants to mature fully, pick the pods in the Autumn. leave them spread out on newspaper somewhere cool and airy (the attic room is ideal), then when I get sick and tired of tripping over them, split the peas (beans) out of the pods & store.
Last year was the world's worst for seed saving - all I managed were some runner beans and some peas. The runners are no good for seed swapping as they easily cross-pollinate, and so won't be a named variety, but they are good for me to grow next time round. And I forgot to make a note of the variety of pea pods saved.
It's a good job that bean and peas are viable for a number of years, so I could use the 2011 seeds.
I spent a very happy evening last week making up envelopes with seeds and labeling and putting in a shoe box, and today took them to Ryton.
In return I have picked myself out a heritage variety of each of leeks, lettuce, pea and dwarf French bean, and a mystery tomato 'latah' that no one seemed to know much about.