This is a cute trick you can do with Firefox that I happen to like.
If you’ve got a bookmark saved in your bookmarks bar, right-click it and choose “properties”; there’s a checkbox there at the bottom, a feature that time forgot, that says “Load this bookmark in the sidebar.” For the most part this doesn’t do anything you’d want, but I’ve discovered that in a few cases, being able to take a quick peek at the mobile version of a site can be surprisingly useful.
So far I’m finding this works pretty well with:
… and pretty much any site mobile/responsive enough to fit in the sidebar nicely.
Keep is particularly useful – it’s one of the best services Google’s built in a long time, but now that I can get in and out of it quickly and it syncs across devices I’m using it a lot. Between this and using BarTab Lite X and Tree Style Tab to put my tabs on the right side of my page, I’ve got web-content front and center, tools to the left, tabs to the right, and I’m pretty happy with that.