When cyclists think upgrade they go to carbon, everything, and nearly every bicycle part can be found in carbon fiber.  But purchasing an expensive carbon seatpost, stem, or choosing the carbon saddle rails over Ti actually yields very little gain in performance.  If you really want to go faster you lighten inertial weight which means moving parts such as wheels, cranks, and pedals.  Until recently there were not a lot of great options to upgrade individual drivetrain components.  You were mainly stuck with the good-better-best of the big three groupo manufacturers.  If you were riding Red or Dura-Ace you were at the ceiling of their performance, and cheap plastic pulley wheels were the norm.

If you compare the actual performance difference between two top tier wheel brands it is very very small, and maybe even non-existent in some cases.  Going from a Zipp to an Enve or vice versa will not make you that much faster as they are already highly developed products.  But there is actual opportunity to drastically improve drivetrain components, which is where the Danish company Ceramicspeed entered the market.  Ceramic bearings were not new, but high quality ceramic bearings were new to cycling and Ceramicspeed has been on the cutting edge of their application.  Because of the hardness of ceramic bearings they must be perfectly round or they will quickly tear into and wear the alloy races out.  Cyclists on a budget looking to upgrade to a ceramic bearing bottom bracket often found they wore out even more quickly and had more issues than a traditional bottom bracket.  This technology demands absolute precision in manufacturing in order to be utilized, but when obtain this standard you now have a component that lasts much longer, withstands abuse better, drastically reduces friction, and has less inertial weight.

Ceramicspeed produces their own hybrid balls made of grade 3 silicon nitride.  It takes well over a month to produce a single ball of this quality and roundness.  They manufacture a very wide variety of bottom brackets for road and mountain that may be purchased in coated and non-coated models; coated bearings reducing friction even further.  Pairing the bearings to perfectly CNC machined alloy or carbon parts gives the components a jewel like quality.  You can definitely feel the difference with parts that seem to want to turn on their own or spin indefinitely.  

Ceramicspeed alloy pulley wheels with ceramic bearings are an easy upgrade over your stock (plastic?) pulley wheels, and are a good place to start optimizing your drivetrain.  But Ceramicspeed now produces the oversized pulley wheel system (OSPW) replacing the entire cage and pulleys with a completely different design.  Specifically made for each drivetrain the oversize pulleys are mated to a carbon cage with, of course, ceramic bearings.  The oversize pulleys further reduce drivetrain suck by limiting surface area or contact with the chain.  And when it comes to the chain there is the UFO line of products (ultra fast optimized).  The Ceramicspeed UFO chain made by KMC is compatible with Shimano, SRAM, and Campy 11 speed drivetrains, also available in 10 speed and Shimano 9100.  The UFO chain is specially coated providing an advantage of a purported 2-5 watts over several hundred miles.  The coating wears off but you are still left with a high quality chain vs the super chain.  The Ceramicspeed UFO chain coating (don't call it a lube) can also be purchased for around $75.  It is a unique, 100% dry coating that hardens on the chain needing to be re-applied every 200k.  Again purported as the fastest bottled chain treatment, superior in friction loss over all other products.

Wheel bearing kits are the next stop if you want to get optimized, and Ceramicspeed makes a wide variety of wheel bearings for most major brands such as Zipp, Enve, Mavic, Hed, DT, and more. They have also recently expanded into headseats and have their own line of greases and lubes specific to their products. 

All of this optimization does come at a cost with alloy pulley wheels starting at $269 and OSPW starting at $499.  The most common question then becomes are Ceramicspeed products worth it.  If you are a cyclists that is fine riding a dirty drivetrain for months at a time these products may not be for you.  Reducing friction by keeping your drivetrain clean is the most economical place to start.  But if you are looking for that slight leg up on race day, or an extra few watts in your next time trial, or a few minutes closer to a Kona slot the investment will be worth it to you.  It is important to note that a bottom bracket that lasts 3x longer than an OEM one does have some value built in.  None of these products singularly will give you a large gain in performance.  But if you were to break the bank and go OSPW system, running a UFO chain, around coated bearing bottom bracket, with a wheel bearing kit...  Weight weenies beware, you just may become a friction weenie.