That would be me. I use a blender. In fact, it's the ONLY thing I've used, for more than 30 all-grain batches, not to mention all the partial mash batches before that. And I have no plans to buy a mill yet. It works, it really does. My beers are what I would call "better than average" and many have won awards. And my efficiency is consistently around 80% for a standard gravity beer in the upper 1.050s. So here's exactly how I go about it, if you are truly interested.
1) Use a 1 cup measuring cup for consistency and ease of use.
2) Put 1 cup, or perhaps a slightly scant cup (as long as it's consistent) in the blender.
3) Put the cover on (this is important!).
4) Quickly pulse on/off/on/off/on/off on a medium setting (again, be consistent) until the grain stops flying all over the place. Once the grain is staying down, keep the blender turned on for about 5-6 seconds.
5) Check the "crush". You want it to look like about 85-90% of the kernels are broken into a half dozen pieces, with a reasonable amount of flour in the bottom (maybe 5-10%), and only about 5% uncracked kernels. Adjust timing as appropriate on subsequent "crushes".
6) Dump the "crushed" grain into your mash tun.
7) Repeat all the above steps for the next 20-45 minutes, depending on the size of your batch, your mash efficiency, and how big a beer you're making. Time consuming? Perhaps. Big whoop? No.
A few other notes:
a) If your blender is too powerful or too large, you may need to use more or less than 1 cup so that you get a homogeneous "crush" without it flying all around inside the blender. 1 cup is what works for my blender. But if you try to crush too much grain at one time, the stuff in the top just sits there and doesn't get crushed at all, while the bottom turns to flour. You need to find the delicate balance between flying grain vs. no movement at all, for your particular blender.
b) If you are using wheat or rye, or any dark roasted grains, you will want to do those separately, as they act different than the more normal base malts and lighter specialty malts. Generally, wheat takes an extra couple of seconds to crush down where you want it, and rye takes an especially long time, maybe 3-4 times as long as normal, as it is so hard. Dark roasted grains, on the other hand, only take a fraction of a second, it seems, as they are so light and dry and fragile. In fact, I usually just crush my dark grains with a mallet in a ziplock.
There you have it.
"This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)