I try not to place any outbound links or add no-follow to them. As was said it is bad for your internal pages.
According to google, you should limit the number of links on page to 100 or less links. However, PR depends on backlinks. If you have 5 outbound links on your page, then every link will have more PR juice[for the page at which the link is pointing], in contrast to if you have 50 links on a page.