It's a bad idea. The reason it's a bad idea is because there is no sustainable competitive advantage and you're putting yourself in a position where Flickr could wake up one day and marginalize your entire business. (At which point it would be a race to the bottom margin-wise, until you go under and they have a monopoly on the service.)
It's funny how the people here on HN seem to equate "thing that would be fun to build and use" with "good idea for a profitable business."
If you have the easiest to use site, that makes people money off their Flickr purchases, then that's sustainable.
It's not like there is any "sustainable advantage" to Google search - they weren't first to market in the space, and they can be beat - but right now, no one can beat them.
It may be true - this app or Google might not last in "the long run." But what's the long run?
I'd say if you made this Flickr converter and made a few million bucks in a year or two, you'd be happy, even if Yahoo smashed you later.
Throwing around business buzz words like "sustainable competitive advantage" and "race to the bottom," and insulting the community to boot, is no way to argue. Take it from a guy who can program and who has a prestigious business degree - you are talking out of the wrong orifice.
Uh, those aren't buzzwords. If you have to choose a project to work on for a startup, one of the first things you should be asking yourself is "what can I do to maintain a slight advantage over my competitors for some reasonable period of time?" This should be one of the first questions you ask, it's a pre-condition.
It might be an exclusive partnership, a difficult to replicate technology, a patent, an incredibly novel or non-obvious idea, something you have domain knowledge that's relatively exclusive, etc. This particular idea has none of these, and would be marginalized overnight if it showed any indications of being a profitable venture.
Also, when setting out on starting a project that's going to take more than a few weeks, you want to pick a really good idea. You only get a few shots at this, particularly if you're going to quit your day job. You'd best prune away ideas that, best case scenario, you expect to "make a million bucks in a year or two and get smashed." Instead, you want to focus on the few ideas you have that you think could become the next Google. Of course, it generally doesn't turn out this way, but you should at least feel that it's within the realm of possibility.
I wasn't insulting the community beyond the posters here who are saying this is a great idea without actually critiquing the business side of things. If I see bad advice, I'll point it out. (Although I'll admit it was a bit snarky, I was just a little taken back by all the "Great Idea!" posts.)
BTW, insulting the poster isn't the best way to argue, either.
There's a difference between pointing out a company that doesn't have a clear advantage and saying that given an idea, it's one worth investing months of effort in despite the fact that it doesn't have one. You need to remember that most ideas you execute on generally fail (and take time in the process of failing,) so you need to be chooosy when it comes time to dedicate yourself to one.
That said, being first is a small advantage, particularly in a new space, but not a great one. The real benefit of being first is making it possible for you to build a bigger one (like mindshare,) but there's a lot more luck involved than if you had just started out on a project where you had an incredibly larger advantage. You don't see the failed versions of Moo, now do you?
It's funny how the people here on HN seem to equate "thing that would be fun to build and use" with "good idea for a profitable business."