create link to another Site

create link to another Site - How-to for Administrators | Google Groups:

> Question...how do I sidebar link to another site? I don't think I
> can create a relative link. So do I create the absolute link with /e/
> or /a/ ?

"This isn't possible at this point because, as you point out, the URL
varies based on who you are. This multiple URL solution is only
temporary. We are working on bringing this all together into a single
URL.

Thanks
Mike
The Google Sites Guide"