Steganography is a poor way to keep things safe. While it may add a layer of protection keeping files on you computer safe from non-technical users, it provides zero security against anyone else. Most forensic applications search raw data for file headers and analyze file sizes - among other things. So, for example, if you were to hide a pdf file in a jpg, this would be useless against someone searching for pdf headers. (It would probably also stick out to have a 25MB image that was 320px by 320px...) Essentially, stenography is useless in modern computing against modern forensic techniques. Also, adding the "." before a file doesn't hide it, it only allows filters that filter out dot files to filter them out. You can still find those files if you ask for them specifically.
As far as the strength of AES, Blowfish, Rijndael, or whatever else - they are only of limited security. Regardless of what anyone tells you, these algorithms are not unbreakable nor were they ever designed to be unbreakable. You're correct in saying that encryption (generally) relays on an algorithm that can be reversed; however, to reverse them it requires a significant amount to processing effort - more than is currently possible or probable to calculate the primes and retrieve the original key.
A good way to think about encryption is to ask yourself, "How much is my data worth?" and "How much effort would someone else put in to getting it?".
If you're trying to hide nuclear launch codes, then popping them in to a text file in a password protected zip file isn't good enough.
The only encryption that is considered by many to be uncrackable is the One Time Pad.
So, how do I hide my stuff?
I would recommend that you download Truecrypt and create a large container that is suitable to hold all of your files you want to hide - then add 30%-50%. Once you've created the container, fill it 30%-50% with files that someone else might think are important, but are worthless. These files will act as your diversion files - a decoy if you're ever forced to reveal your password.
Once you have that set up, create another hidden container within the first. This is where you will put your super secret files. (Refer to the Truecrypt docs to find out how to do this - it's easy.)
Finally, rename your file with a different file extension to throw people off the trail. The .dmg extension on OS X is good for this - or even .iso. Again, this is of limited use, but makes some people feel better.
Now you have a pretty secure container that hides your files and if you're ever put in a situation to reveal your password, you can reveal the password to you decoy partition and no one would be able to prove otherwise. Rumor has it that the FBI wasn't able to crack a Truecrypt container even after 2 years.
Now if you really want to take things to the next level. Get a USB with a passcode, and use FileVault2 to encrypt your USB and put your Truecrypt container on the USB.
I also have a moat with rabid sharks, but YMMV...