Glad to see one of those links is Magnetic Rag. That's my favorite.

Most people I know who like Chopin also like Rachmaninoff (his Preludes are a good place to start; if you don't mind a cellist joining in, the Cello Sonata is amazing) and Brahms (Op. 118 is a favorite). I also recommend everyone listen to Schubert's Sonata D. 960 no matter what else they like.

Lately I haven't been playing much besides Scriabin's early works. I don't think he gets enough credit -- there's a lot there. The Op. 11 Preludes are a good starting point. (The Op. 8 Etudes, the first three sonatas, the Sonata-Fantasie, and Fantaisie in B Minor are the others I'm slowly working through. He's probably my favorite composer at this point.)

Are you interested in contemporary classical? Rzewski is fantastic. Try listening to Winnsboro Cotton Mill Blues or The People United Will Never Be Defeated (8-video live performance, or a good recording in a single chunk ).

As far as stuff more like Joplin, you might like Art Tatum. I'm less knowledgeable in that arena (not that I really know that much about classical music).