If you have lots of keywords and you want to use them in the ad copy, with the rest of the ad being the same for one to another, you can do it youself with {Keyword} substitution (tips for this throughout webmasterworld).
If your ads really need to be significantly different from each other then your budget will dictate the amount of work you need to do.
If you have a relatively small budget then you're in for a heavy typing session.
If you have a high budget you can give spreadsheets to Google and they'll process them for you.
In my experience, there are limits to what they'll do for you. If the account handlers think you're going over the top with the number of ad groups / campaigns they'll try to get you to simplify your plans. This sometimes makes sense - if you have thousands of ad groups ongoing maintenance can be a nightmare.
Col
If you are asking about mass-submitting *ads*, i.e. creatives, I don't know if this is possible other than through your account manager. PowerPosting lets you submit hundreds of *keywords* at a time (my recent experience was that I could only submit about 20 max if I didn't want to get the login prompt).
Ash