This app was mentioned in 4 comments, with an average of 1.25 upvotes
There is already an app that covers it to a good extent: https://play.google.com/store/apps/details?id=com.nearify.android
If we are going to have a thread here, I'd prefer to see things that are not covered there.
I use a few different sites. On Android I recently found this app which is not to bad, https://play.google.com/store/apps/details?id=com.nearify.android&hl=en
I also use Facebook and search the events feature it has and tick interested for everything so it adds to my own calender on Facebook which I export to Outlook so it all Syncs up calendar wise.
Websites, I checked out all my surrounding councils as most have an events calendar pages similar to the ones below; some sites I use to have bookmarked no longer work as the season of events has finished though the ones below do work so you could start with them and see what else you find along the way. Some of these sites also allow you download the information as a file so you can add it straight to you Outlook calendar which is handy.
Canning; http://www.canning.wa.gov.au/Month/
Subiaco; http://www.subiaco.wa.gov.au/Things-to-do-in-Subi/events
Fremantle; http://www.fremantle.wa.gov.au/whats-on
Victoria Park; http://www.victoriapark.wa.gov.au/calendar
Rockingham; http://www.rockingham.wa.gov.au/events
Some others are;
Perth Concert hall; http://www.perthconcerthall.com.au/whats-on/this-month/
Northbridge Piazza; http://visitperthcity.com/northbridge-piazza/events/next-7-days
AroundYou using Perth search; http://www.aroundyou.com.au/perth
Weekend Notes; http://www.weekendnotes.com/perth/
Next site seems to have most major events from councils listed though does not list the smaller events; http://www.omi.wa.gov.au/omi_events.cfm
Eventfinda; http://perth.eventfinda.com.au/
EnjoyPerth; http://www.enjoyperth.com.au/this-month
Perth Arena http://www.pertharena.com.au/Event_Calendar.aspx