One of the lesser-known features in Area 51 lets you generate little sidebar-ad-sized images to promote proposals you're interested in, like this one:
To use it, click the "Share This" link under the number of followers/committers and look in the bottom half of the pop-up. It'll give you the URL for an image that is generated dynamically, and so is theoretically good indefinitely regardless of when you post it.
The script that generates these images still works for sites that have already entered beta. I just saw the following at SDLtridionworld.com:
I think it looks a little weird to have "n days in beta" in the same place as "new site proposal." It's also possible to view even more misleading images for old proposals that have closed down (e.g. Firearms) or graduated into full site-hood (e.g. Arqade):
Can we alter the script that generates these a bit, so that they're more suitable for all the stages a proposal might actually be in (definition/commitment, private/public beta, &c.)?
For beta sites, we could replace "new site proposal" with something like "beta Q&A site" (and then change "view beta info" to "view site info" so the word "beta" doesn't show up three times), and for closed/graduated sites we could return a generic A51 ad. I'd rather not 404 anything entirely and cause broken images on the sites of people who were, at least at one point, attempting to support us.