[terminalveracity]

This feed contains the main articles from the print magazine. Some of the miscellaneous topics (Your Shot, Wallpaper...) don't parse properly and are removed.

Spoiler:

import re
from calibre.web.feeds.recipes import BasicNewsRecipe

class NatGeoMag(BasicNewsRecipe):
    title                  = 'National Geographic Mag'
    __author__             = 'Terminal Veracity'
    description            = 'The National Geographic Magazine'
    publisher              = 'National Geographic'
    oldest_article         = 31
    max_articles_per_feed  = 50
    category               = 'geography, magazine'
    language               = 'en_US'
    publication_type       = 'magazine'
    cover_url              = 'http://www.yourlogoresources.com/wp-content/uploads/2011/09/national-geographic-logo.jpg'
    use_embedded_content   = False
    no_stylesheets         = True
    remove_javascript      = True
    recursions             = 1
    remove_empty_feeds     = True
    feeds                  = [('National Geographic Magazine', 'http://feeds.nationalgeographic.com/ng/NGM/NGM_Magazine')]
    remove_tags            = [dict(name='div', attrs={'class':['nextpage_continue', 'subscribe']})]
    keep_only_tags         = [dict(attrs={'class':'main_3narrow'})]
    extra_css              = """
                                h1 {font-size: large; font-weight: bold; margin: .5em 0; }
                                h2 {font-size: large; font-weight: bold; margin: .5em 0; }
                                h3 {font-size: medium; font-weight: bold; margin: 0 0; }
                                .article_credits_author {font-size: small; font-style: italic; }
                                .article_credits_photographer {font-size: small; font-style: italic; display: inline }
                             """

    def parse_feeds(self):
        feeds = BasicNewsRecipe.parse_feeds(self)
        for feed in feeds:
            for article in feed.articles[:]:
                if 'Flashback' in article.title:
                    feed.articles.remove(article)
                elif 'Desktop Wallpaper' in article.title:
                    feed.articles.remove(article)
                elif 'Visions of Earth' in article.title:
                    feed.articles.remove(article)
                elif 'Your Shot' in article.title:
                    feed.articles.remove(article)
                elif 'MyShot' in article.title:
                    feed.articles.remove(article)
                elif 'Field Test' in article.title:
                    feed.articles.remove(article)
        return feeds

Note:
The other National Geographic recipes make use of the news feed: http://feeds.nationalgeographic.com/ng/News/News_Main

This recipe uses the magazine feed: http://feeds.nationalgeographic.com/ng/NGM/NGM_Magazine