Comixology
A lot of people, including myself were pretty upset at Comixology last month when they sold out to Amazon and then removed in-app purchases. Forcing everyone to go to the website kind of sucked. After doing it for a couple of weeks now however, I don't think I mind it. It's faster and I like loading up a cart full of stuff before buying. While the opportunity for discovery has been reduced, my comic purchasing has increased.
I'm sitting at about 338 issues right now, which is a lot of reading. I'm hoping that with Amazon now owning Comixology, we continue to see the great sales they've been having lately. There have been some great issues for $0.99 that are well worth the price.