I particularly like the "Equity Trainer" tool in Equilab where you could tell it a range for Hero and Villain, and it would pick a random hand from Hero's range and show you a random flop. Then you have an equity slider to try to guess how much equity that hand on that flop has against the range you used for Villain.

When you're in the mood, create your own mini-game and play until you get bored of it. It trains the gut to recognize how flop textures intersect with Villain's range. I found it often eye-opening to play that game. I'd get on a hot streak and guess 3 - 4 in a row, then the 5th one, I'd be off by 15%, and I'd be asking what I missed.... so helpful.