It seems a little bit like you're trying to create a more structured version of what people are already doing on Twitter with many of the trending hashtags. (e.g. today's #failedmcdonaldsproducts[1] or #100factsaboutme[2]) Rather than fight the momentum Twitter already has there, perhaps you could take advantage of the Twitter API to automatically pull these trending topics in as Thingist Lists. When a new list is auto-created from a trending topic, you can automatically tweet out a link to the Thingist list with the same hashtag, which will get you exposure among people following that term.
The hard part then is making sure Thingist provides a more compelling experience than Twitter for browsing these sets of things. I'm not sure if you're there yet, but there is definitely an opportunity to do something better than search-by-hashtag. If you do pull this off, you'll have plenty of fresh content to keep new users engaged until they start creating lists right on Thingist.