This add-on makes opening JIRA issues really easy. I like it!

One click, paste the JIRA ID, Enter, and voila, a new tab containing the issue. Neat!
For an unknown reason, the latest version as of sep2016 does not work anymore (the button is not there anymore). This will need a bugfix. In the meantime I've installed "JIRA Issue Opener Paste & Go" and it works.