Invasion Problem 1
This position is from Game 4 of the 30th Kisei title, between Hane Naoki (black) and Yamashita Keigo (white). Black has just invaded the lower right corner in sente and now an invasion on the left side is urgent, to make use of Black's thickness in the top left.
I (Alex) figure this is a good position to use for an invasion problem because the commentary in Go World #108 (by Yamashita himself, although he's White) explains why Black chooses the invasion he does. Since this is not a life-and-death problem, however, I propose having a sub-page to discuss each of the moves A-F, instead of the usual "Attempts" and "Solution" pages.
I'll give people a few days to try to explain why they like or dislike certain moves, and then start adding the ideas from the game commentary and some of my own thoughts.