I discovered Penzu from a Twitter post by one of my friends on Twitter and I definitely think it's worth recommending. Penzu is a private journal & diary that can be used on a daily basis for anything you want to write down. One great thing about this service is that it's completely private. Other people won't have access to your entries unless you specifically permit them.
Isn't this just another blogging thing?
What makes Penzu different from blogs is primarily its interface and functionality. It's not complicated, nor is it messy. You have your writing space shaped after a ruled piece of looseleaf paper, and buttons to save, print, share, insert images into your entry. These are dated entries meant to be accessible by only yourself.
It's online based, so what if can't get online?
This is clearly a drawback of having anything online based, but most people have free access to the web almost all the time. I've been looking to start writing a private journal and I've considered both having it handwritten in a notebook and having it stored online. I chose the latter method simply because I have internet access all the time. I tested Penzu on my iPhone and it functions just like it should.
Yes, if you're an owner of a PDA phone (or an iPhone/iPod Touch), you already know that you can use the built in application to store your thoughts, and so forth. I look at it this way; A single interface on both my computer and mobile device while having it all backed up online is more convenient than having to manually backup all the time. If you've been looking for a private online solution to spill your thoughts out onto, Penzu may be perfect for you.
UPDATE: Check out my updated review of the latest Penzu offerings here.