Anyone know of something like this for linux?
The xfce4 window manager, at least, already does this. Probably most do but I can't verify right now.
Deppend what distribution you are using. By default I see that generally have 2 or 4 desktop enables. You can change with shortcuts Alt+Tab or Ctrl+Alt+(Right/Left)Arrow. If you are using a popular distro you should have on the panel something like this (you see here desktops to the left of Trash, in this case):
Or you could add this doing Right click on panel, and choice "Add to Panel" option, and after Workspace switcher.
If you want to change the number of desktops you can do this with right click on you Workspace switcher/Properties/ and choice the number of desktops that you want. This works on Fedora, Ubuntu and others gnome distros.
If you want more for a gnome based distro you should see this link
If you have a kde based distro you should see this link
And for xfce based distro use Xfce menu > Settings > Workspaces Settings.
For later questions, it is better if you say which distribution or desktop environment you are using
I'm using Slackware64 with Enlightenment 17, and if I middle click on the desktop anywhere, on any screen, it pops up a list of currently running programs to switch to.
If I just click on the desktop, anywhere, I get the system menu up to run new programs from the menu, in my case the KDE menu.
Admittedly, this is not on both monitors at the same time, but wherever my mouse cursor is, it pops up the menu or list of running programs (list includes all programs running on any monitor) and my visual focus is usually where my mouse pointer is.