Is there a task switcher (Alt+Tab) for Xfce that allows to select application using a mouse click?
You can use Skippy-XD for this. It is a full-screen task-switcher for X11 similar to Mac OS X's Exposé feature, and works nicely with Xfce. To install latest development packages (recommended), use the Skippy-XD PPA (daily). In Xfce 4.10 you can easily bind skippy-xd command to Alt + Tab in Settings > Keyboard > Shortcuts.