Best source of free images? My top 2 sites.

Having wrestled with producing a conference presentation today, I found myself up against the clock trying to find suitable - and fun - images. I resist all most temptations to fly in the face of copyright so that means Google Image search is a no-go. In the past I've seen many sites recommended and have amassed a collection of bookmarks but, these days, when it comes down to it I'm just using these two. Mainly because I am most confident I understand their licence terms and I find they do the job:

Morguefile 
Pros: Images are free to use, including commercial use, and require no attribution. The least fuss option!
Cons: The site kept bombing out on me a bit today with intensive use but if you are patient, it seemed to work again. Also, not the widest selection of images - have to be creative with search terms. Some produce weird results!

Compfight
Do a search from the main page, then I usually opt for "Commercial" license.
Pros: I like the interface, searches well and you can scan results quickly; better standard of images than Morguefile.
Cons: you need to attribute. I don't mind this on presentations or blog posts but it can be messier on publicity materials. I've also had them subsequently re-used without attribution.

As an example, here are some ones I amassed when planning our "Managing your online presence" session for students. Aside from a couple of genericky ones, most of them are to illustrate what you wouldn't want a potential employer to find if they search for you on social media (the drunk dancing bunny-man is my favourite). I'm hoping to share all our materials on this and had the idea of using Pinterest to group the images as they aren't mine to share but could be helpful to locate. I've been really enjoying using Pinterest for arty stuff but this is my first time using it for work.

Do you have a favourite source of images? Let me know in the comments if so - tips gratefully received!