SanDisk managed to cram 200 GB of storage space into a microSD card just two years ago. That amount of storage space on a semi-rugged piece of consumer electronics the size of a pinky nail is still pretty amazing, but the company has doubled that capacity with the 400 GB Ultra microSD UHS-1 card.
The tiny card meets the UHS-I standard with its ability to read at up to 100 MB/s, and is also fast enough to earn an A1 rating for application performance. That means you're guaranteed at least 1500 read IOPs and 500 write IOPs so you can use phone or tablet applications stored on the card without fear of major slowdowns.
If we assume that a microSD card is a rectangular solid measuring 0.59" long, 0.43" wide, and 0.039" thick (15 mm x 11 mm x 1 mm), we arrive at a displacement of 0.165 mL. If we assume that we can pack 75% of the volume of a 2 L soda bottle full of microSD cards, that means 9090 cards can fit inside. This little bit of napkin math leads to the conclusion that 3.63 PB of data could be funneled into a waterproof soda bottle. We truly live in amazing times. The manufacturer says each card can hold 40 hours of 1920x1080 video, enough to hold three copies of the extended cuts of all three Lord of the Rings movies, so the hypothetical 2 L bottle full of cards should be enough to fit all three of The Hobbit films.
SanDisk's 400 GB Ultra microSD UHS-1 card is shipping now for $250. We found a product listing at Amazon, but it appears to be back-ordered right now. Gerbils should probably check the specifications of the microSD slots on their phones before throwing money down on the table for this mind-boggling dense piece of storage technology. The sum sounds like a lot of money at first, but freedom from hearing complaints about full memory cards is a valuable commodity.