The other nice thing is that you can create it once, and then duplicate it as many times as you like for free.

If you make a table or some nice drapes, they're still just one thing, yours alone.
However, if you write an application that does something useful, you can improve the lives of thousands to millions of people all at once.

I think the best I've personally achieved so far is a noticeable improvement for hundreds (maybe a few thousand, I'll have to check my webserver logs), but the potential is there.