These pictures are courtesy of Kitchen and Bath design, and they show some wonderful uses to perk up cabinets. The first one shows the use of a visually appealing curved glass cabinet that adds a completely different element than just the standard sharp corner cabinet.
Here the use of beveled glass and lighting adds architectural detail and and really kicks it up a notch. 
Don't really want to see totally through the glass doors, but just a hint of what's behind?, add semi opaque glass for some obscurity.
Have a peninsula? Want to retain a view? Want to make the kitchen seem bigger and airy? Don't want to loose cabinet space.? Try having both sides of the cabinets in glass, this is a great way to use natural light and have access to both sides of the cabinet. Instant beauty.
Here's another view of the use of clear glass see through cabinets. Notice how light this feels, another use to maximize the natural light.
Want to break up a wall of wood? Then using glass door fronts may just be the answer. Another option here would be to have solid wood fronts on the lower half and reserve the uppers for glass fronts, add ambient lighting and you have a dramatic look to your space.
Storage and beauty, imagine the difference if this was all in solid wood. Here the use of glass fronts creates a beautiful buffet.
Here the use of ribbed glass doors can lend a bit of a contemporary clean look.
Find the texture of glass that suits your style.
This kitchen really needed to break up the whole white wall look. By using glass fronts, this adds visual interest to the whole project
This two tone kitchen with beverage center in black with leaded glass, gives the look of a furniture piece, creating a high end look.
