I'm new, not a pro and never will be and need decent flash for all around use. I have a Nikon D80 with a Nikkor 18-135 and a Sigma 12-24 and have no idea what to get. Please help.
"all round use" is kinda vague.
Probably most flexible is SB600 or SB800 or SB900 (in order of ascending price). SB400 also possible for short distances (eg. friends at dinner table).