I don't mean this to be derogatory or anything, but just to clarify the situation for the sake of a more appropriate answer, I get the impression from your surprise that you don't fly often, and that you might be in a hurry for at least some sort of answer, even if it's incomplete or maybe not even 100% accurate (up to date). So based on that:
The 3 oz. limit is for stuff you're carrying in your cabin carry-on. No limits on stuff in checked baggage. One tip: Fluids in checked bags should be sealed inside zip lock bags (with all the air pressed out) for your own protection, in case they leak. The air pressure changes can do that.
At one time, all your 3 oz. containers had to be non-opaque. (Lost track if that's still the case.) Containers have to be carried in a separate clear plastic bag (zip lock type preferred) no bigger than one quart. (Still the case, last I heard. Never paid much attention since I try not to carry on fluids any more.) At one time, there was also a max on the total amount of liquid. No idea about now. There are also exemptions for prescription medicines and infant formula. Your ticket should have a link to the TSA/Homeland Security web site listing more details as to exact limits (if you're interested or feel like you need to know). Sorry, don't have it handy right now.
Alternatives: Many hotels have taken to supplying more toiletries since there's more demand, especially from business travellers on short trips who don't want the bother checking baggage (or potential headaches, if you get unlucky). Some people, particularly on longer vacation trips, will go to a store at their destination for the more commonly available toiletries, to avoid the hassle of carrying it yourself (i.e. weight and volume), and leave it behind at the end of the trip. (Smaller containers have become more popular because of this.)
Also (probably not terribly relevant to you, but since you mentioned it), quite a few manufacturers have recently started selling stuff in <3 oz. quantities specifically because of these limits.
Best of luck.