Removed my profiles from moikrug and vkontakte: it was fun, but managing the same friend network in four places is pretty strange when you think of it. So I guess I'll stay with LinkedIn, feel free to add.
Update regarding vkontakte (01/2011): wow, people keep hitting this post when searching for "delete vkontakte account". The comments below are outdated, and the up-to-date instructions are here. They're basically saying that you can't delete your account permanently, and instead you should
- change all your contact info to meaningless placeholders
- go to "Мои Настройки > Приватность" ("My settings > Privacy"), select "Только я" ("Only me") wherever applicable and hit "Сохранить" ("Save").
That doesn't really help from e.g. friendship requests from friends of friends, but oh well.