Barbara Hambly is an excellent writer of fantasy.  She freely mixes real-life humor into her work to create a truly realistic milieu.  Needless to say, this is also one of the authors who I feel had a great impact on my own style of writing.  She is a master of what is commonly referred to as the "crossover" novel, where the main protagonist is someone from our own world who is transported by some means into the world of the novel.  If you have never read this author's work, you've truly missed a great experience!

• Dragonsbane  
• The Ladies of Mandrigyn  
• The Silent Tower  
• Those Who Hunt the Night  
• The Time of the Dark  

Ask any author to name the other authors whose work influenced him, and the chances are very good that Robert A. Heinlein's name will be on that list (if not at the top of it).  I am no exception.  As a boy, I grew up reading the Heinlein juveniles and, I believe I can honestly say, that Robert Heinlein started me down the road that led to becoming an author myself.  I've listed a few of my boyhood favorites by the greatest legend of American science-fiction.

• Citizen of the Galaxy   One of the Heinlein juveniles.  A "rags-to-riches" story in which the main character goes from being a down-on-his-luck backstreet thief, to becoming a crewmember and then a junior officer aboard a merchant "family" ship.  A moving story of honor and duty.
  
  
• Farmer in the Sky   Another of the Heinlein "juveniles".  This is a frontier story of a teenage boy who travels with his family to begin a new life on Gannymede as farmers.  Heinlein captures much of the flavor of an Old West frontier epic while still maintaining himself solidly in the realm of futuristic science fiction.  Of course, we now know that, if anyone wanted to build a farm on Gannymede, it would have to be a hydroponics farm, but this is still an excellent work.
  
  
• Have Spacesuit will Travel   Possibly the most famous of the Heinlein juvenlies.  This is a near-future story about a young, teenage boy who wins a spacesuit as a consolation prize after losing the grand prize of a trip to the new space station.  Dejected, he goes for a walk in his new spacesuit only to be abducted by aliens and caught up in a web of interstellar intrigue and conflict.  He is able to save the galaxy and his new friends return him home in time for dinner!
  
  
• The Moon is a Harsh Mistress   This work classifies as more of a "young adult" novel than a juvenile.  This is a story of how the moon, which is being used as a penal colony by a united Earth, wrests its independence from the mother planet.  An action-packed study of revolution, ideals and civil liberties that is as fresh today as the day it was written.  If you haven't read this one, you need to!
  
  
• Starship Troopers   There is no way this work of Heinlein's could ever be classified as a juvenile.  Starship Troopers is a gritty, down to earth and hard-hitting story of war told by one who lived during World War II.  This novel shows better than many others that, no matter how advanced your technology, no war can be fought without the front line "grunts".  As Heinlein's troops themselves say, "...planet busters are impersonal.  We make the war personal..." This work of Heinlein's has recently been made into a movie.  It remains to be seen how good a job they did on it...