Dave's Garden has (had) such a system, run by Robin, but iot got to be too much work. I thought I could do it, but it turned out to be way too much work for me.
The system over there was centralized, and many members sent seeds they had gathered, or partial or full pkts of commercial seeds they no longer needed. Robin (or I, briefly), would split them in to smaller pkts, label them, and sort them into categories.
When new members noticed the thread and asked for seeds, we would ask their preference (crops or flowers, annual or perennial, grass, trees, vines etc). Then send 10 or so pkts for postage.
That system saves a lot on postage! But it turns out to take some time and a little space to store and sort seeds. It reminded me that I was already over committed on time for other tasks.
I never thought of a way to divide the 'central' stash over several people and share the work.
Over here, I would be glad to volunteer for the specific job of splitting up big bags of seeds into 2x3 Ziplocs and labeling them, then forwarding them to someone with time to do the rest.
(I'd also contribute 2x3 Ziplocs & bubble mailers - I have a ton.) Sometimes people who collect their own seeds sent enough for 20-30 1/4 tsp pkts.
I could contribute many small pkts of these saved sees:
Pacific Giant Delphinium (light blue / pale purple Delphinium elatum OP Perennial)
Broccolo Spigarello (Italian heirloom leaf broccoli)
white annual sprawling Alyssum (Lobularia maritima) Looks most like: 'Snow Crystals', reseeds
And smaller numbers of pkts of left-over commercial seeds
Lobelia
Tomato
Carrot
Radish
Bells of Ireland - Lake Valley Seeds for 2011
Foxglove/Foxy Mix - Lake Valley Seeds for 2011
Hollyhock Seeds - Lake Valley Seeds for 2011