I think the solution is a combination of tactics. A curated "getting started" or "best of" list is a good way to get eyes on some of the best posts that are representative of the blog. Make good use of categories and tags, and use lists of related posts to make navigation between similar posts less painful. On my blog (http://grokcode.com), I also have a prominent "popular today" section on the homepage so people can see which posts are getting the most traffic at the moment (these are rarely the newest posts). http://www.alistapart.com/ has a curated "editor's choice" section on the homepage that is frequently updated and help draw attention to great content from the archives.

Also, the standard blog format uses entire posts on the homepage and archive pages, but everything is so much cleaner and easier to navigate if only post summaries appear on those pages.