I recently saw a little windows application called vistaswitcher. It is alternative window swticher for windows vista na 7. In addition to replacing alt-tab it prevents alternative keybinding to right mouse button + mouse scroll and some interesting keybindings: you can mark any windows in the switcher and then perform operation on your selection-> for instance close all selected windows by pressing x key or minimize with m key. It is rather interesting and i would like to recreate this behavior in the kde. However there is one problem: selecting windows is not so simple if you need to hold your alt key down so this app provides option to not automaticly close the switcher once you release the key (in that case you need to press escape or switch window). I have no idea if this is even possible with kde window switcher. Any hints?

I don't think any of the switchers do multi-select, but there are some which you can activate and interact with to some degree. In particular the Present Windows effect/switcher will display all of your windows in a grid, of sorts, and then you can use the mouse or the keyboard to close or activate windows of your choosing.
I would guess that it shouldn't be too difficult to add multi-select capability to this switcher, if you know a bit of coding.

Windows effect/switcher will display all of your windows in a grid, of sorts, and then you can use the mouse or the keyboard to close or activate windows