To be more specific on the PCI issue, IBM actually developed the MCA bus because they didn't feel PCs could compete in the server market, and PCI of course changed all of that, and it was developed by (gasp!) Intel in an effort to move their chips into the higher end markets, and they used EISA as a kind of bridge between the two camps. The original use for PCI busses was to create SMP i486 machines to run Novel Netware on, but that has obviously since changed significantly. As an aside, PCI was actually designed on Sun workstations using the bus that PCI would eventually replace - SBus.
And on the 640k of memory thing, that again wasn't IBM, that was actually Intel and Microsoft. While 32 bit processors can address 4,294,967,269 bytes of memory (4 GibiB), the 80286 that DOS made the most headway on used 16 bit addressing, limiting it to 65,536 bytes of memory (64 KibiB), but using some nifty tricks it was alocated in ten byte segments, giving rise to the 640 KibiB memory limitation (as opposed to the 64 KibiB on the older 8086 parts). When MS moved DOS into the 386 with its 32 bits of virtual address space, they left the first 640 KibiB as a kind of legacy section for 16 bit processes and then used Extended and Expanded memory to fill the gap upwards (Expaned used larger pages and 16 bit addressing of those pages and Extended actually used 32 bit addressing) as well as the high memory area and created the need for the 15-16 MB memory hole. All of this was Intel/Microsoft, IBM didn't have anything to do with it, it was simply a design limitation of the processors that got built into DOS and has been with us ever since, even though all of the way back to the 386 Intel's chips could put 16 bit address space anywhere it wanted in the 32 bit address space, Microsoft left it down in the first 16 bits of conventional memory.
Now you might be asking, what has IBM thought up of? Well, if you own a laptop made within the past ten years, pay homage to IBM. With their ThinkPad, they changed the face of laptop making by creating a form factor that everybody uses today. Like your keyboard? Again, IBM. Also, the keyboards that today are considered the most rugged and have the most tactile feel and best layouts are IBMs, as they have been since the days of the IBM Selectric. That little pointing stick in the middle of your keyboard on most laptops and some desktop keyboards? Thank IBM again, it actually increases productivity by up to 20% (you don't move your hands from the keyboard), and since the patent ran out some years back everybody's been using it. RS232? Partially IBM, if not completely. ATA? IBM again for the most part did alot of work in the begening, hence its name being drived from the PC/AT. VGA interface?... did you think it was nVidia? Parallel ports? The floppy drive interface? The size of your motherboard (ATX is simply AT rotated 90 degrees)? APICs for dual processing (IBM had alot of invluence in this one)? Warm-swap devices (ThinkPad 760CD) and PCMCIA (IBM ThinkPads)? The shape of your power cables? Size of the expansion slots? Size of the expansion bays? Need I say more. IBM has had its had quite mucking around in the PC industry since they invented it, and the laptop industry as we know it as well.