I'll break things down a bit for ya Ham.
DD (direct damage)
DRG, SAM, WAR, DRK, THF, MNK, RNG, NIN, BLU
Magic Damage
BLM, RDM, BLU
Tank
PLD, NIN, WAR(mostly pre-40, but is fully capable of tanking until 75 subbing MNK or NIN). Some HNM Linkshells use RDM/NIN.
Support
BRD, COR, RDM
Other
BST, PUP
None of these are perfectly steadfast categories. BST has A- axe skill and gets basically the same WSes as warriors, but they don't have access to all the damage equipment that wars do, but pets do make up for quite a bit of that discrepancy. I know basically nothing about PUP, can't really comment.
As far as you not wanting to tank, choose from:
SAM, DRG, DRK, MNK, BLU, RNG, BLM(not invited to parties often anymore, gonna solo a LOT), THF(not a widely used job anymore). These are your damage dealing classes. You're gonna want to take WAR to 37 for subjob purposes. Also, NIN to 37 most likely as well. WAR and NIN can both DD or tank, and will do both.
Good websites with a ton of information:
Final Fantasy XI :: Dreams in Vana'diel - use the forums
Main Page - FFXIclopedia - a Wikia wiki - omfg I love this site. More than you could ever want to know about FFXI.
Order of the Blue Gartr • Index page - high end LS's forum, think of it as the FoHguild/EJ of the FFXI world.
Oh yeah, this is Spheric from in game.
