Is there a shortcut for inserting a <%= %> in Rubymine?
I took a look in keymap and didn\'t see anything.
The default shortcut is Ctrl+Shift+Period on Windows and Cmd+Shift+Period on Mac. It may not work on all the keyboards, in which case you can change it in Settings (Preferences on Mac) | Keymap: Main Menu, Tools, Erb, Insert <%= %>:

You can also use code completion:

After accepting this choice you'll get:
<%= | %>
Another option is to define a live template:

Type re, then Tab to expand.
Finally, you can define a keyboard shortcut for any text/template using the following trick:
Edit | Macros | Start Macro Recordingre, then TabEdit | Macros | Stop Macro RecordingRubyExpression nameNow go to Keymap settings and assign a shortcut to RubyExpression under Edit, Macros.