As a daily metacognitive tool, you can use leaning logs in many, many different formats.  Perhaps the most used is a very basic journal technique.  Towards the end of class every day, time is set aside for students to write in their journals.  Usually during the last five minutes (more if the time is warranted), students take out their learning log journals and record what they have learned for the day and how this ties into their everyday life and things they have learned in the past.  In order for this to be effective students must really think about the day's lesson.  I like to use the some of the following questions for students to answer:

Today's date:

What is the most important thing I learned about today?

How does this tie-in to yesterday's lesson?

How does this fit with the objectives set forth for my grade level?

What specific use could I have for what I learned today?

Since we all know that students learn better if they know what they will be learning about and why they need to know it, this approach keeps students focused on the relevant part of each lesson.

These logs can be used across the curriculum in any subject matter.  I have seen their effectiveness work recently.

Other approaches and uses:

Dialogue Logs is an adaptation on the traditional learning logs.  This can be a fun way to change-up the everyday "blah" that can sometimes occur in a daily lesson.  After students write, ask them to trade logs and comment back to their partners.  Peer response can be very motivating and makes writing more social.

You can use learning logs for assessment in knowledge of content, knowledge of process and knowledge of personal feelings about these items.  Using Blooms Taxonomy®, Learning Logs encompass at least 5 of the 6 tiers of the framework of learning.