Shouldn't the code/language/libraries used or even the title stand out more than the picture?
Other than that, pretty cool idea.
I'm sorta GitHub star hoarder, have starred 1.9K repos at the moment. I use that to track libraries I'm interested in (and their counterparts in other languages, for inspiration), projects addressing the same niche as the ones I'm working on... GitHub star-search is good, but can be made even better. And also some projects I don't want to forget about are not on GitHub — and I'd prefer to have a single place to store all those in a searchable fashion.
Such project I would use on a daily basis (or I'll have to write one at some point in future).
Are you affiliated with the project somehow?
That's almost enough to power a medium-sized JavaScript app these days ;)
Also, will it make the full READMEs of the projects searchable? Astral (the one from the comment above) seems to search only in projects' taglines, which is definitely not enough for me...