So I'm a bit curious about these really general ''download content'' type PIN submit offers blowing up lately.
What kind of ''stuff'' can I promise the visitor to download? I never see any restrictions on these offers.
Can I promise something that isnt real?
When running these offers think broad interest.
What do the masses want?
TIP: Look at the top 10 music videos, top 10 apps, top 10 games, top 10 music singles, top 10 books, whatever, top lists are your friends in this case 
I'm carious too! As i don't see any restrictions on the offer's details!
I guess in these cases it's always better to ask your AM to be 100% sure.
The landscape changes a lot, depends how much heat that offer is getting atm.
If it were for the advertiser there would be no limit, too bad there are regulations or they lose short codes.
When it comes to what you can run and get away with.. for these offers it's pretty much anything goes as long as it's not absurd. Such as advertising guns or sex.
As for angles, think offers that are doing well now, and broad things like attilla said. Something i also play with often is "apps that can't physically exist, but would be cool if they did" type of angles.
and I'm slowly growing from there. These angles are getting me sick CTRs
In this case ,Ask your AM for 100% sure, since you do not know the CONVERSION FLOW,they might no paying you if you done wrong !