I think Sram would be nice as the default mem type in pc's, just think of the speed.
OTOH, IBM recently demonstrated a holographic data storage system. lots of layers of 1024x1024 pixels = lots of MBs can't remember the specifics (I was semi-sleeping during the opto-electronics lecture). Just like star trek.
On the subject of embedded DRAM: Sony has a chip design with 256-MBit (32 Megabytes!) of embedded DRAM.
The device contains 256-Mbit of on-chip embedded DRAM, or eight times more than the current Graphics Synthesizer. The DRAM and wide 2,000-bit internal buses can deliver 48 gigabytes per second of bandwidth.
I had inadvertently started a thread on this topic in the Off Topic forum before I realized this one was here so my vote is for Magnetic ram. read it here