From the unconventional and awe-inspiring to the hilarious and heartwarming, here's a look at some of the most interesting photos, videos and stories that have our newsroom talking today. What's capturing your attention, filling your inbox and cluttering your Facebook/Twitter feed? Tweet us the stories you're talking about using #InstantIndex, or email us at ABC.WorldNews@abc.com, and they could appear on World News.

ABBA Considering Reunion Tour An ABBA band member has revealed the group is considering a reunion tour to mark its 40th anniversary. Until now, the band had turned down a reunion, saying it wanted fans to remember ABBA as it was in its heyday.

(Michael Ochs Archives/Getty Images)

Grand Canyon Fills With Water The Grand Canyon flooded today with enough water to fill 30 Olympic-sized swimming pools an hour. Federal officials are opening the floodgates to let the Colorado River flow. The river is now swollen with sand thanks to monsoon rains this summer. The experiment will move that sand, creating new beaches and sand bars, giving families more room to camp and vacation next year.

ABC News ' Amy Robach Reveals Breast Cancer Diagnosis ABC News' Amy Robach revealed today that she'd been diagnosed with breast cancer after agreeing to a mammogram on-air for "Good Morning America." On Thursday she will undergo surgery. Today she had a powerful message for anyone who has ever procrastinated about getting a test or ever wavered about taking action. "The whole reason why I walked into that van was to raise awareness, for people to get mammograms and little did I know I would be a walking example of how having a mammogram saved my life," she said.