Slashdot
m.slashdot.org/ (HTML5)
Slashdot is a venerable (founded 1997) user powered tech and politics news site, which was recently acquired by Dice.com. Slashdot stories, as well as polls, questions and book reviews, are submitted by users. Other users can vote stories up and down and leave and rate comments. Randomly selected user moderators can label stories and comments as interesting, informative, off-topic, flamebait, etc. Stories are primarily assigned to the front page by Slashdot editors rather algorithmically.
The current mobile version of Slashdot has Stories, Polls and Firehose tabs but no UI for accessing Slashdot's tags or categories. If you don't like the mobile webapp, there's a link to the Desktop version in the mobile page footer.
Slashdot Mobile is optimized for iOS and Android browsers. It also works well in the Firefox and Opera Mobile browser but not in Opera Mini, where only a blank page is displayed. There's a legacy text-only mobile version that works in all browsers at slashdot.org/palm/.