Somebody was asking about Moszkowski op.72 #6 (the chromatic runs etude). It is quite difficult, I find, at the level of most Chopin etudes. Good recordings are Horowitz and Pletnev. Op. 72 #11 is the most famous, very fun to play and listen to. It's difficult, but once you get the notes, they fall pretty well under the hands (bringing it cleanly to top speed is tough, though). Op. 72 #13 is not known but very beautiful : it's a study in double notes with a powerful Russian melody, deep, melancholic and all that... Hamelin has a good recording of it.
Now for daily exercices for the advanced pianist, have you guys heard of I. Philipp ? He was a famous piano teacher (performer and composer as well) at the Paris Conservatoire end of XIX beginning of XX century, contemporary of Saint-Saens, Ravel etc. He published under opus number 8 a daily set of exercices for the advanced pianist ("Exercices journaliers") that are very effective and original in my opinion. The basic principles : the book is divided in mechanical devices (scales, trills, wrist staccati...), and each device comes with several exercices and several examples of use in the repertoire for further practice (like this, you get to use what you learn right away in the most horrible sections of pieces that you are very likely to come by as a performer). For instance, if you are in the octaves section, you have a couple of exercices to help you improve, plus several excerpts from famous pieces with octaves (Chopin op. 53, Liszt Hungarian Rhapsody #6, Beethoven Waldstein...). Very useful and highly recommanded.
Now I don't know where to get it (I have an old edition from 1946 given to me by a teacher), but I recommand you llok for it.