[sarahj]

A few ideas from a quick brainstorm, none of them are perfect, but neither is the centralized server solution:

1. Bookmarklet - In a similar vein to the way some password managers work you could construct a bookmarklet that the user can click on to make a site do the right thing - there are some security configurations depending on your threat model - however this does require user interaction.

2. Browser plugin - like #1 but obviously with the pain of writing and maintaining a browser plugin.

3. Bake the site determination into the flow - so instead of a 1-click retweet it becomes a 2-click retweet with the second step requiring the user to provide the site where they want to retweet - again some security implications and breaks the regular flow (although you could get around this by doing it once and storing the value in a cookie)

4. Have a local app listening on a specified port (so retweets get POSTed to 127.0.0.1:7000 for example) and then from there onwards - requires extra setup, makes the system less portable (can't just throw it on a hosted server). Like #2 but more annoying.

[nstart]

Number 3 is pretty good honestly. It might be the best option in fact.