Thinking ahead for sites in the future, has anyone been able to mitigate the length of a sandbox penalty by setting up a new domain with a coming soon-type page and then just linking it from a few other sites so it gets indexed and letting it sit for a while? Could this potentially mitigate the length of the sandbox penalty if you did this for several months before you actually put the real site up?
I would suggest putting some relevant content on the page. It doesn't even have to be in a final form and it shouldn't take you that much longer to do. Using the text "Coming soon" would be an easy red flag to catch. If you aren't going to put content on the page, at least use a gif that has "Coming soon" so the bot can't read it.
Yeah I am trying it out with a site right now and basically have a description of the kinds of things the site will be showing soon. Good point on the coming soon text. And I am going to flesh it out with a bit more information.
It can't hurt to register the domain as soon as you think of an idea, then get something relevant up with a plan of what is to come. I've not done that, but I have "reused" domains that used to be something else and avoided the sandbox.