In a different vein, I'd like to recommend "Boomerang Audiomagazine". It's been described as NPR's "All Things Considered" for the 6-12 set. It's available as a mail-out CD or cassette-tape subscription, or as an audio download through Audible.com or iTunes.com. If you go to the
BoomKids website you can listen to a sample issue. It's awesome for car rides and bedtime listening after lights out. No, it's not directly stretching reading skills (though there are a lot of benefits to literacy-enhancing skills like new vocabulary, critical thinking and language comprehension), but it does give kids access to a lot of material that they might not choose to read for themselves... politics, economics, science, geography, mystery stories, nostalgia stories, biography, etc. etc..
Miranda