500 lines of what? 500 lines of APL / J / Q is enormous; 500 lines of Haskell / Scala / Ruby is quite a mouthful, 500 lines of Java or C is rather moderate, and 500 lines of assembly is precious little. Also, since a line of code can contain zero or more statements, something like cyclomatic complexity, or just statement count, could give a better measure. (Edited: fought autocorrect.)
Oh how I'd like a compilation of 500L APL programs.
Maybe some of the APL mavens can do the existing examples in APL and explain them. The write density of APL is pretty amazing. Depending on what you are doing a clear winner at code golf.