Site-wide outbound links.... The sites I linked to are all relevant sites in the same niche and some of my visitors may find them useful. Again, I am in a position of balancing the needs of my user versus the needs of Google.
Beyond the PageRank issues, site-wide outbound links might suggest to Google that there's a special relationship between the linking site and the destination sites. The arrangement can look like a linking scheme (and often is), anything from friends mutually patting each other on the back to purposeful attempts to game Google.
If you think about what's most useful for your users, you might decide that a relevant link from a specific article in your site to a specific article in another site, one that's been carefully selected, would probably be much more useful to your user, then and there, than a site-wide link. That's the way I'd look at all of your linking, on site and off.