Marvel have selected 700 #1 issues of their comics and have put them up for free in a limited run lasting a couple of days and available from their digital store. The Promo is running Sunday March 10 and runs 11PM Eastern Time on Tuesday, March 12. After time runs out they will then be priced, but still available.
The promotion details are here
I never really got into the Marvel comics, where I grew up had no comic shops, I only ever saw the cartoons. I'm looking forward to seeing if I can and download a few of them and see what they are like.
Odds are that the digital shop will crash under the load of several million fans all logging on to try and find their favourites.