The title says it all, did you ever give access to your account to anyone?
If so, to whom and why? Did you then change your password after they used your account?
I'll start by saying that I did, but my wife and myself were using the same account since she was a very casual player. And I know she has safe security practices since she's interacting only with very few people in-game, so no risk of information leak. And I set up her comp so that the shortcut uses the "-pwd" option so she never really knew the password (and her comp is fully protected).
EDIT: another question you may want to answer is: did you ever give access to someone so that they can power-level your characters? (i.e., play the game for you so that you don't have to do what you consider boring stuff, for example get to level 20 with all your heroes at level 20, or achieve 1 million+ gold)
EDIT: if you can create a poll for me on GWG and it's not against GWG rules, please contact me.
EDIT: updated information from 97 answers so far (up to message #114). Note that numbers are rough estimates, because it's hard to guess the information from natural language descriptions

The who?
1) Absolutely not: 36 (37.1%)
2) No but I considered it: 7 (7.2%)
3) I refused access given by to others to their account: 2 (2%)
4) To close friends that I trust: 34 (35%)
5) To people I know in person: 12 (12.3%)
6) To family members: 23 (23.7%)
7) To someone I met in game: 4 (4.1%)
8) I also have access to other people's account: 18 (18.5%)
Average number of other people that can access acount:
107/97 = 1.1
Motivations (the why?):
1) To check something for me: 2 (2%)
2) Shared account: 2 (2%)
3) To increase one of my title or play the game for me: 9 (9.3%)
4) For special events (e.g. festivals): 7 (7.2%)
5) To try the game in order to decide if I should buy it: 6 (6.2%)
6) For storage: 2 (2%)
7) Just because I trust them (or they trust me): 14 (14.4%)
8) Someone gave me their account: 1 (1%)
9) Only for a particular event or situation: 13 (13.4%)
10) For playing the game with different maxed characters: 1 (1%)
11) In order to be able to play while I was banned[I]: 1(1%)[/U]