I'm going to a summer BBQ  party thing with people on a committee I am apart of. It's this weekend and I just got an email saying all of the "BBQ Fare" (meat) will be provided and that somebody else will be bring salad, appetizers, and drinks, and that we should email them with whatever else we are contributing to the meal. 

I'm just wondering if you think I should bring something on top of my own veggie burgers or is that enough right there considering I won't be eating any of the other "bbq fare?"

It's really up to you, but personally I'd say it was polite to bring enough food to share, because it is an event where that's what is expected. Also, I guess I would feel like even though I don't want to eat the other food, it's being offered/shared with me, so I would want to reciprocate.

Lots of people enjoy vegetarian food even though they are not vegetarian, if you're not confidant others will enjoy veggie burgers, maybe something like a pasta salad, or just crisps, or drinks, or something else would be appreciated. :)

I think that would be enough, if you think that there's going to be enough other stuff you can eat.  Bringing foil wrapped potatoes for the bbq would be a good idea too, cheap enough that you could feed everyone if you had to.