API allows Users to take their catalog with them

[samgreenlee]

Reposted from the Shareable article:

I completely agree. If the various services do not find a way to
collaborate, there are only two possible results:
1. They become increasingly competitive (which would be ironic) until
one or two services dominate the industry.
2. They all die.

Can I put a request out there? I am building a sharing site for my
church and had to modify a classifieds WordPress theme to do it. There
is no chance that I will be able to implement an API with the site,
given that I am not a very experienced code developer and that it
probably will not work with my current site.
As this API gathers steam, could someone please create a way (maybe a
free or inexpensive WP theme) for independent organizations to easily
build enclosed sharing sites/libraries of goods and services that can
be private but allow users to take their info and personal catalog
with them on different sites? I am thinking of one user being able to
join separate sharing sites for neighborhood, church, school, and
city, without having to re-catalog all their items.

-Sam