Bard
The class that can do a little of almost everything, just not so well. A lot of people think they suck, though this only really reflects on their support class feel, even without the powerful healing of a cleric or druid.
The primary focus of bards is their party-buffing "Bardic Music" ability, which when combined with a high Charisma score and lots of ranks in Perform, can work wonders for a combat-heavy party. A bard can also easily enter the Dirgesinger class (From Libris Mortis), if you feel inclined to play an emo-rockerboy who summons undead. (Be warned, you may lose the will to live.) If your party is interested in roleplaying, the performer/scoundrel aspect of the bardic class offers lots of opportunities for acting in character. As bards are the quintessential fantasy musicians, roleplaying a a drunken, semifamous bard could be quite rewarding, and even more infuriating to your party. As noted above, bards combine some of the elements of almost every class, but the price they pay for versatility is ineffectiveness. Bards will never outshine any core class in their specific role (unless you use splat-books, like most people do now, and with the possible exception of party skillmonkey), but make suitable fill-ins for almost any class. Bards are rather good in traditional rogue missions (Break into this castle, steal shit, come back.) because of their ability to cast arcane spells and wide range of class skills. Of course, a Arcane Trickster could outdo a bard. Bards are, however, pretty pathetic in simple combat. A bard cannot fill the place for a barbarian, fighter or ranger; he cannot hope to match the combat abilities of these more martial classes... without splatbooks. (Am I the only one that's heard of Snowflake Wardance?).
(Get with the program people. 90% of 3.5 classes are better fighters than the fighter. Excluding the bard, who simply sucks at everythin- DISREGARD THAT, I ROLLPLAY.)
Since bards are traditionally rolled to make other members of your party groan, they are masterfully applied to the gnome. If you need proof of their magical ability to annoy, think about the dirgesinger. Think about how they can take "Perform: Gong" as their instrument.