What do you mean by "explore"? You mean how do people find out about these apps? Usually word of mouth, online forums, stuff like that.

Even five years ago, the global programming community wasn't that large. If someone built something small and useful, and they promoted it in their local community (like at a LUG, Perl Mongers, other meetup) they gained decent usage and exposure.

I am trying to document some at mobilewebappsftw.tumblr.com because finding apps on the web is incredibly hard.

You also have places such as Chrome Web Store and Firefox OS Marketplace