If the giveaway is for someone internal, I'd say make sure it adds value is desireable (not a cheap pen or old marketing swag). If it is something you'd want (potentially a gift card, cash, extra vacation day, etc.)
If the giveaway is for a customer, make it meaningful. Perhaps it is a 1 year subscription for free, a free product, something limited (that can't be bought from your company) potentially a tour of your facility, autographed version of your product, or free swag (t-shirt, stickers, etc.).
Keep in mind, the more unique it is, the more desireable and coveted winning it will become. So keep it interesting.
There are quite a lot of great giveaways but this depends on the need. For example, If you are looking for corporate giveaways in bulk, Personalized Office supplies are really great. If you are looking for something to giveaway for a potential client or business partner, a gift basket or hamper is quite nice. You can actually search online for great gifts that can be delivered to Australia or to other countries. :)