Rach 1 cadenza when the theme is played in chords.
Cziffra's trill in Mazeppa (greatest trill ever)
um thats all i can think of at the moment
YES! That trill is SO. COOL.
I agree with the Rach 1, and here are some others:
Alla Marcia in Rach 2, if played correctly
Ending movement of Mahler's 9th, where it seems like death is rapidly approaching but someone at last comes to terms with it and dies peacefully after looking out on one last sunset over the lake
2nd Movement of Ein Deutsche Requiem, when the main theme is brought in with a powerful crescendo
In Mozart's Requiem, when after about 40 seconds of orchestra, the choir quietly sneaks in and slowly starts building up on itself...chilling!
In Durufle's Requiem, the organ conclusion is extremely haunting. I heard it played live once, and even though the choir had failed to make much of an effect in the movement before the last (it was only a college choir), the final movement deeply moved me...of course, the organist was brilliant.
Liszt's 2nd concerto, at the beginning of the triumphant finale, and then again at the end with the wildly impressive brass melody
As for really catchy, there are some good parts in the major-key sections of Franck's Symphonic Variations, and I frequently find myself humming them in my head.
"Gypsy" Melodies (just a few): E minor theme from HR 10...I love how it appears quietly and almost daringly; HR 14 or Hungarian Fantasy, the middle section (particularly in the HF, when the violin and other instruments--what, clarinet, oboe, a few others?--take over); Cziffra's Roumanian Fantasie, when the last melodic theme occurs for the first time. That sort of music really gets me going!
Finale to the Grieg concerto, and the ending of the first movement for that matter...plus, a lot of other moments in the piece that I won't pick apart right now.
Beethoven's op. 111, the gradual build up and dying away of the theme...beautiful, all of it.
Liszt, Second Ballade: the introduction to and continuation of the final theme in B major.
I could go on forever, heh...but I'm not going to...