Originally Posted by PJBentham
I tried creating my own Custom view titled "On Sale!" and then went to mysite.com/On-sale!/ and still nothing, just a 404.
Did you specify in Store > URL Settings the URL structure for your custom view(s)?
If you specify let's say related-products for the Related Products custom view the page will be accessible via yoursite.com/related-products/
After changing the URL settings don't forget to update your store first by clicking the [Update Settings Only] button.