The life in SEO, it's so on the edge.
I've finished experimenting with a technique. I now have only two sandboxed sites at this time, and I'm in no hurry to get them out as they are both in development. I'll share my experience with you, but use of the second technique is at your own risk.
There may be a couple of things that you can try and have worked for me, but it is safe to warn you that you are playing with fire here. Use at your own risk and there are no guarantees in SEO. Don't come back crying to me if you try this and get penalized. I'm talking about situations where you have no choice to get a web site out of the sandbox right now.
First of all, and the safest way, is to keep an updated Google Sitemap, make sure Google verifies it regularly. Make new pages everyday, modify your sitemap to reflect and force feed it to Google. Make it all seem sooo natural. They provide the tools to do this. Make new content daily and force it to spider the sandboxed site daily. Try this first for a couple of weeks then ... if all else fails, try this.
If the web site is able to migrate easily, embed it in a historically credible web site. Put it a couple of levels deeper than the Entrance page. Provide one link to it from the host domain entrance, make sure the spider can find it, not in it's face but casually mentioned in the content, naturally looking. Make it look innocent. What this appears to do is stimulate the duplicated content filters because the content exists exactly somewhere else. This causes a respider to the sandboxed web site and a positive reaction can occur at this point. Google has to decide which is the better content, the sandboxed or the non-sandboxed. Do not alter the sitemap for the host domain. Make it look like you had an idea and then changed your mind a couple of days later. Check the host domain cache, when you are certain that it has found the link, remove the link and the embedded site immediately after they both get re-spidered. Now the sandboxed site has the best content by default and seems like it can get out of the sandbox because of this.
Ethical SEOs will point out that what in fact is done here is similar to creating ghost pages. I have to agree. It isn't exactly ethical and I do not endorse it.
Now some clever SEOs are thinking to themselves, ah duplicate content, naughty naughty and up for penalization. Not necessarily. Google instructs us ( not in these words of course ) that duplicate content naturally exists on the web and will provide results according to which one it determines is most original and has the best content for the keyphrase search.
Remember too folks, it may have been coincidental that I tried this technique at the same time that my web sites were scheduled to get released. If you try this and it doesn't work, well, it was an idea that didn't work for you. Perhaps a better one than what you may have in your own head if you read this far down the thread. :rolleyes: