Forwarding Multiple Domains.

I have one main domain

www.domain.com it has pretty good PR, ranking and things.

I also own many other domains that do not have websites or anything but are similar to my current domain, plurals, domains that go with the same theme.

What are the risks of forwarding these domains at the register level, is it ok, horrible idea.. ?

 

Just make sure they use a 301 redirect and not a 302. As long as it's a 301 you are fine.