When you link out in your blog posts, use convention where applicable and creativity when warranted, but be aware of how the links you serve are part of the content you provide. Not every issue you discuss or site you mention needs a link, but there's a fine line between overlinking and underlinking. The best advice I can give is to think of the post from the standpoint of a relatively uninformed reader. If you mention Wikipedia, everyone is familar and no link is required. If you mention a specific page at Wikipedia, a link is necessary and important. Also, be aware that quoting other bloggers or online sources (or even discussing their ideas) without linking to them is considered bad etitquette and can earn you scorn that could cost you links from those sources in the future. It's almost always better to be over-generous with links than under-generous. And link condoms? Only use them when you're linking to something you find truly distasteful or have serious apprehension about.