I can't think of a single good technology that originated at Sun
ZFS, dtrace ?
Yep, those two, and how about network file sharing in general, including the various versions of the NFS protocol, and the YP/NIS/NIS+ systems that provided (for their day, anyway) secure and scalable directory services and access control?
How about bringing the best of both the Berkeley and AT&T System V Unix worlds together, with the guidance of the author of BSD, one of the most brilliant computer guys ever?
How about the first 64-bit hardware and OS that didn't require you to completely rewrite your apps and libraries to take advantage of that great new hardware? How about compilers from a computer manufacturer that actually didn't completely suck?
How about the open source graphical user environment (OpenWindows) that in the early days of Linux, finally gave it a GUI that didn't suck, and arguably transformed it from a schoolboy's neat hack into an alternative OS that could grow to run a fair fraction of the world's computers?
How about the very concept of corporate-sponsored, open source software in the first place? (Not just trivial fluffy stuff, but the actual guts of the system and services that run the computer and the network, including several mentioned above, eventually extending to things like OpenSolaris, Spring, and OpenStep.)
How about supporting networking and networked apps from the very beginning? - How about realizing that "The network *IS* the computer"? How about being one of the very first to adopt and support new high-performance networks? (3Mbps ->10Mbps Ethernet, FDDI, built-in 100 Mbps Ethernet, ATM, FibreChannel, etc.)
How about the first reasonably priced, small, scalable, lighting-fast storage array, with hot-swappable disks and compatible with the expensive industry-standard volume and disk management software, but also usable with free/inexpensive Sun "Solstice" alternatives?
And then, of course, there's Java itself. I'm not a huge Java fan these days, given the rise of things trying to do its job better, but there's no question Java is solid and runs important chunks of the world, and is largely responsible for the widespread adoption of object-oriented programming, which was previously a niche thing for the Smalltalk and LISP guys.
Oh, I almost forgot...
How about mice that required you to not twist their mirrored mousepads? (yeah, I know, SGI used those, too...)
How about the ridiculously goofy and expensive 13W3 video connectors and cables?
How about the rackmount Ultra servers that destroyed the CD tray if you ejected a CD with the door closed?
How about computers that really *were* the size and shape of a Pizza Box, but were strong enough support an 80-lb 24-in HDTV monitor on top?