One thing that is starting to annoy me is the number of services that start out free, but then as soon as they become popular they introduce paid-for features while slowly reducing the free features until they are virtually useless.
The stock response to this is "well, it's free, what do you expect?". However, this oversimplifies the issue and ignores all the other aspects of the problem. Most important of these is that I've recommended these services to others, thus giving the free service its userbase. My comments on these services are still on the internet, but I wouldn't recommend them now. I've also spent my own time incorporating their service into my apps and my time isn't free. Their services are now so entwined in my apps that it's going to take me lots more time to remove them and find alternatives.
I've got no problem with these services charging for extra features, but reducing the features that were there originally is almost tantamount to blackmail.