as i understand it, it is in some circles, especially if written as "d00d. (pl, d00dz).' commonly used that way by script kiddies and other hacker wannabes. not being one of them and not frequenting IRCs, i can't say from personal experience, but i've seen plenty of references to the practice while reading geek news.
having lived in non-english-speaking countries for the last 20 years, i often have to ask for guidance about such matters when i go back to the states for a visit. so i don't have any real answers, and i doubt there's a good one other than using the person's name.
as far as i'm concerned, 'man' is fine. but it doesn't solve the problem -- it's an ejaculation (pun unavoidable -- n., an abrupt emphatic exclamation expressing emotion) and not a term of address. ('man, indigo, that was an amazing story.') personally, i have no problem with 'guys' in the plural, used among familiars -- most american women i know use it that way among themselves. but i don't have a good answer as to what to use in the singular. in a restaurant how should one get the attention of the person who brings the food? 'oh, waitperson!" sounds ridiculous, and 'server!' conjures an image of a central computer. i suppose that's why they often introduce themselves, using their first names, which strikes me as overly familiar.
anyway, i'm cool with dude or man. 'babe' might work if there were a lou reed smilie with audio (doo duh-doo duh-doo ....).