I did it for one of my sandboxed sites .... I just copied the site map of sandboxed site A onto site B, put some internal links on site B to the site-map ---I called the page "Site B's Portal to Site A" - tidied it up a bit, made some changes to avoid duplicate content. The page will probably be a high PR4, so its valuable deeplinks to site A ..... this is the sort of thing that Google are forcing people to do to get out of sandbox ..... site is now out of sandbox (also did a lot of other things as well)

I did notice a newish directory (sorry did not bookmark) offering to do exactly this --- ie host the site map, called it "XYZ Directory Portal to Site X" --- gives deeplinks to all parts of the site.

CBP