Is there a keyboard shortcut to bring up Finder?

By default, no, there's no keyboard shortcut to activate Finder.

Keyboard Maestro can do this though:

It's actually easy. On Yosemite, just press option ⌥+command ⌘+spacebar. That will open a new Smart Finder window. You then can navigate from there. It works on a system level no matter what application you're running.

No need for scripts or complicated setups.

Turn this option on in System Preferences > keyboard > shortcuts > spotlight > "show finder search window" in recent versions. This can be mapped to other keys too, but it can cause conflicts in other apps that might be using your desired shortcut.

1. Open Automator and choose the service template.
2. Change the input type from selected text to no input.
3. Add a Launch Application action and drop Finder on the pop-up button from /System/Library/CoreServices/. (The dialog for choosing an application does not allow selecting Finder.)
4. Save the service and give it a shortcut in System Preferences > Keyboard > Shortcuts > Services.

The service only opens a new window if there is no existing Finder window. To open a new window every time, add a Get Specified Finder Items action, drop the folder you want to open on the list, and then add a Reveal Finder Items action.

Automator is included in OS X: http://support.apple.com/kb/PH14303 (Mavericks), http://support.apple.com/kb/PH11360 (Mountain Lion), etc.

Background: http://en.wikipedia.org/wiki/Automator_(software)

Further reading if you're interested in doing more with Automator: http://www.macosxautomation.com/automator/

Actually I find it easy to bring up the finder with COMMAND-TAB. Cycle thru the open applications till you have selected Finder.

If any windows are already open but hidden they pop to the front if none are open a simple COMMAND-N opens a new window.

Not exactly a simple WINDOWS-E but it does work.

You can always use this trick to open Finder..

alt + command + <space>

This is actually a shortcut to search for files IN FINDER MODE, In other words it opens Finder directly without needing to install any tools.

You can add your favorite directory onto the sidebar (Finder > System Preferences > Sidebar) and access it easily.