Bard/sorcerer - both use Cha to cast spells, but sorcerer levels don't have much else to offer. The sorcerer has worse hp, BAB, saves, and skills than the bard. The sorcerer spells are not going to be as useful as the bard spells you would have gotten with further bard levels. And you'd suffer ASF when casting sorcerer spells if you wear armor. Maybe one level could be worthwhile, to get unrestricted access to sorcerer scrolls/wands, but that's more cherry-picking than multi-classing.
I can definitely see a bard taking levels in either fighter or rogue, in order to focus more on one aspect of the bard's abilities (fighting or skill-use). Unfortunately, the 3.5 bardic music abilities are tied to your class level, so you lose out on spells and music if you go that route.
I can definitely see a bard taking levels in either fighter or rogue, in order to focus more on one aspect of the bard's abilities (fighting or skill-use). Unfortunately, the 3.5 bardic music abilities are tied to your class level, so you lose out on spells and music if you go that route.