It would be nice to be able to dual-class Summoner and Bard... *hint hint nudge nudge* :>

Other classes I can think of apart from the standards aaare...
Dancers (Basically physical Bards with more offensive capabilities than healing.)
Brawlers (kind of standard-ish/common but still. Uses gauntlets.) [s]Oh dual class Dancer-Brawler would be interesting...[/s] 
Mechanics (Electric traps, support summons, turrets, all that stuff)
Puppeteers (Pretty much a Summoner, but with more of a direct control, I guess? Limited to only one summon? That kind of thing.)
Spearmen (...Spears.)

Uhh there's definitely a lot more, but people on here are creative so I'm just gonna leave it to the others to add the ones I can't really recall from the top of my head. xD