A learning diary - or as I call it here, a journal - is a good possibility to review what you've learned. Just by writing about your thoughts to a specific topic you are thinking about everything again and by that are somehow forced to remember. Since the current semester is almost over, I can evaluate my learning diary writing now.
I must admit that it was quite difficult to write something regularly. And this is mainly because it is quite time consuming, especially in the beginning. Thinking of, that I would do this for every course I have during the semester (that was the plan at the beginning), I would be quite occupied with writing. But again, this is a matter of practice. I wasn't really used to do this kind of writing, so I had some difficulties with my first entries. Now, at the end of the semester after I wrote some entries (but still not as much as I wanted to), it's slowly becoming easier.
I actually like this and I will try to keep on writing this journal during the rest of my master studies. Especially when using wordpress this might be very helpful for me. For example using hypertext to connect old and new knowledge looks interesting to me. Also the possibility to go back to old entries and add or alter them is great.
I used this of course with my computer. I logged in and wrote some entries. But I also used this with my BlackBerry. This is great when I am on the go. I can write some entries while I am waiting for public transport and this way use the time for something meaningful.