Offer a site map to your users with links that point to the important parts of your site. If the site map is larger than 100 or so links, you may want to break the site map into separate pages. src: http://www.google.com/support/webmasters/bin/answer.py?answer=35769
There isn't really any such thing as too many outbound links. Google has requested that you place no more than 100 links on a page so that Googlebot had an easier time crawling your page. This may not even be true anymore given that any forum has more than 100 links and gets spidered just fine. Most webmasters won't like exchanging links with a site that places huge numbers of outbound links on a page because it dilutes the amount of PR that gets passed to their page. They'd be happiest if there were only one link on the page: theirs. My advice is to put how ever many links you want/need on a page to get what ever job your working accomplished. And yes, outbound links can definately affect your PR. If you link to enough bad neighbors and disreputable sites, you'll find yourself with a grayed out PR meaning you've been booted. This will affect your ranking as well because you will no longer even be in the race, and then you can't even be the last result. I'd pay FAR more attention to WHO your linking to than how many links you're putting on a page.
I second what was said above -- I think that links are dependent on the value that people add to their content for their users. If you are placing links to sites that are excellent resources, I believe that the amount of link love you will receive will be much higher as well as your Trust Rank in Google's algorithm. Wouldn't you trust a site linking to good material? It's like creating a hub page that links out to many -- a prime piece of the algorithm powered by Ask as well as other engines. Just remember, get rid of all NoFollow tags, search engines won't look at your site as reputable if all your links are no follow and those links all lead to excellent resources.
in my opinion, using less then 10 outbound links is good. your pr will pass the other sites with outbound links