As long as you are linking to other reputable sites then there should be no reason to use the nofollow attribute. Many people believe that juice is lost regardless of the attribute but many believe that you actually can help your ranking by linking out because a page about 'Cats' for example linking out to 3 other reputable sites about cats.
The reason you shouldn't really need to use nofollow is that you are making the links which are relevant to the page, and the chances are these are reputable links which outbounding them should help your own rankings. If you think they are not so reputable and don't want to share the PR then simply use a nofollow. Many people use nofollow to combat spam so that they do not pass more rankings to the site than they need to, in the hope they don't spam... but as you know this doesnt stop them ;)