Ok...the Yuuzhan Vong. They are a humanoid race from outside the galaxy (presently unknown exactly where). They utilize nothing but living creatures in thier "technology". Everything from thier ships to their weapons to their clothing is a living thing. They consider mechanical technology to be an affront to their gods. They belive that the prime god, Yun-Yuuzhan, cut off parts of himself to create the other gods and the Universe. Thusly, they embrace pain as virtuous and mutilate themselves as a show of devotion and/or station.
They have several castes. The warriors, priests and shapers being three of the main ones. Shapers are those who spend thier lives genetically altering a myriad of species and organisms to become what they want.
The Republic had their hands full combating them at first. They employ creatures known as dovin basals in their ships and fighters. They manipulate gravity, allowing them to give the ship thrust, manueverability and defense. Defense is in the form of the dovin basal creating a small gravatic anomoly (like a small black hole) to "suck in" laserfire and torpedoes. They are also useful in ripping the shields off of Republic ships. The Republic has been able to counter this by expanding the inertial compensation field around their ships to bolster the shields and by utilizing a chain-linked firing system. Several "stutter blasts" are fired at the Yuuzhan Vong vessel, causing the dovin basal to concentrate on providing defense. The ship loses a bit of speed and control momentarily. Once overwhelmed with the "laser darts", the dovin basal is unable to protect the ship against full-force lasers or torpedoes.
The other interesting aspect to the Yuuzhan Vong is that they are utterly absent in the Force. Jedi cannot sense them or use many of the tricks they'd use on other sentients. When a Jedi fights a Yuuzhan Vong warrior, it is often an even match. While the Force can give the Jedi increased speed and reflexes, it cannot help one anticipate the Vong's next move.
What is really wonderful about this series is that the bad guys are almost understandable. They are not evil for the sake of being evil, but truly believe that it is thier right and responsibility to rid the galaxy of the "infidels". Also, unlike so many other series, where you know the heroes will live no matter what they have to go through...many main characters are dying in this one. The Yuuzhan Vong have taken over a third of the galaxy at present, and they don't lok like they'll be stopped soon. Coruscant is in ruins and many important worlds (Ithor, Kessel and Dathomir to name a few) have been either destroyed or changed. The Vong are like the Nazis in a way, and this invasion is chillingly close to the invasion of Europe in the '30's and '40's.
All of the galaxy's big players are out in force in this series as well. The Imperial Remnant, the Chiss, the Hapans, the Hutts...I'm waiting for the Ssi-Rukk to show up!
I highly recommend this series, even if you're not a huge Star Wars fan. It is excellently written, involving twisted politics, romance, action and moral issues. Luke's struggle to keep the Jedi together with pressure from all sides (including within the ranks) is a fascinating angle to this as well.
If you do wish to read it, you really need to read them in order:
Vector Prime
Dark Tide I - Onslaught
Dark Tide II - Ruin
Agents of Chaos I - Hero's Trial
Agents of Chaos II - Jedi Eclipse
Balance Point
Edge of Victory I - Conquest
Edge of Victory II - Rebirth
Star by Star
Dark Journey
The series is slated to wrap up in 2003
Hope this has been helpful.
