The numbers from last cycle are public knowledge: 435 applications, 20 of which we funded.
Does YCombinator each semester fund 20 or sometimes it is less?
Also, who are the other organizations like YCombinator?
They fund however many they think are qualified.
Techstars directly copied the model, Seedcamp is inspired by YC and invests a little more for a bigger stake.
Two VCs, Lightspeed and Highland Capital have summer programs for student entrepreneurs.
Don't forget YEurope.
Apparently, Hacker News user "enki" started this one if I'm not mistaken.
Last season they had around 10 companies. These were the top 5%. So I gathered there were two hundred applicants for that season.
PG says in another comment there were a lot more than before (probably because of news.yc), so maybe double that for this year.