Here's a free one, Cryptic - weekly C-Store deals.
With little to no C-Store promotions going on, and people often begging for another big sale, why not introduce a weekly promo, where every week you would sell a different C-Store item or service at a discount?
The advantage would be - like with many promotions of this type - an explosion of interest, but the key is for it to be regular. For example, personally I don't often buy games from Steam, but I still check its main page every single day to see what new deal is being offered or if it's the thing I'm looking for, for the price I think is affordable. I.e. more traffic.
With C-Store weekly deals you could have a regular newsworthy material to pique people's interest, even if they wouldn't end up buying a given item. Others on the other hand might feel encouraged to buy a given item while its on sale, which sometimes works wonders when someone didn't even consider buying such item in the first place. Not to mention, it may work even better for both Cryptic AND the consumers to have such items at a discount over the course of time, rather than just doing a single big sale for people to lose their money all on at once.
The only disadvantage I can think of are all the complaints regarding the items that would be put on sale, or their price, but that's unavoidable. Personally I still think it would be better than nothing. A single item with let's say 15-20% discount every week isn't that much to ask, I'd imagine.