If you use Last.fm, you may have got
around to using their events feature where you can search for events
near you and mark yourself attending those events. I was manually
entering the information into my google calendar, which was a pain.

Fortunately, being one of those hip, friendly web2.0 websites, Last.fm
allows you to get your data out in all sorts of useful ways, including
you event calendar as an iCal file. Google being useful, allow you to
display external iCal files in your calendar. Can you see where I’m
going with this? To get this up, log into you Google calendar, go to
“Manage Calendars”, then “Add Calendar”, then “Public Calendar Address”.
Finally type in the url of your last.fm iCal file, which will be http://ws.audioscrobbler.com/1.0/user/dpash/events.ics,
although obviously you need to change dpash to your particular last.fm
username. Now, you only need to mark yourself attending a gig to have it
show up in your Google calendar.

You can use something like this
to get it into your Evolution calendar.