Before I got my 7-string, I just tuned one of my guitars in B. It doesn't sound as good as the real thing, and doesn't make soloing really enjoyable, but it gets the job done, somewhat.
One advice, use a set of .013 or maybe even higher. And have the truss-rod adjusted properly.

You can do the same thing with a bass. But in both cases, keep in mind that you might have to file out the nut of your guitar, to fit the heavy gauge strings. If you don't do this, the nut will break.

Greetz, TK

[Edited by trendkillah on 10-12-2001 at 06:13 PM]