Creative vain brainstorm.

Hi guys,
I've got a different sort of question for all of you today. I'm
looking for ideas on a project to present my skills (as I've been
working hard recently to push myself beyond current limitations)
hoping for a brighter future. The thing is that after a ton of
brainstorming with other people and even more googling it seems that
everything worth doing in rails already has a gem/plugin for it.

I'm fed up with fiddling with the 100th app in my "sandbox" folder
that will never see the light of day and/or is reinventing the wheel
for the sole purpose of self-betterment. This time I'd like to get
even better at what I'm doing creating something that will be useful
for someone else not just me bragging over a beer to my php coder
friends how awesome Rails is.

I know its kinda offtopic but I'm desperate for ideas guys. I need
something that isn't the next attempt at social networking or
something common like that (not that it's bad or anything. It's just
that every coder I know at some point at least thought about doing
it) .

Thanks in advance,