There are many ways to help students reflect.  They could use Blogs as have already been described in the presentation section.  Here is a more managed example.

Provide a learning journal to help students to reflect on what they have been doing.  At Cramlington we use a learning journal throughout each module of our Learning to Learn course.  All students must fill in this journal and hand it in for feedback.  The journal is simply a publisher document with questions in and space to type reflections.  Different sheets are used to reflect on different lessons.

We use Learning Journals in a number of subjects in a similar way and in some cases just a simple template which students can download and fill in as part of a single lesson rather than over a whole unit.

Here is an example of such a template (click on the image below), this one was used to help students coming into year 11 reflect on their performance in year 10.  You will need Microsoft Publisher to be able to open this file.  If you do not have Publisher the image will give you an indication of what the template is like: