This is a great question...one which I've had to deal with in the past myself. I usually like to design a really well crafted "booklet" that is kinda like a brochure about my eLearning philosophy. The most recent one I did (which I used for the job I have now), I broke up into three section:
My philosophy for good eLearning
My philosophy for eLearning project management
and, My philosophy for good eLearning design
I've gone ahead and attached the section for project management as an example. This has been very successful for me. It allows me to give them something that explains the way I think...AND it something I can talk through with them. It also provides a lot of peripheral benefits...for example, it show them that I can design something that looks good and is well written/communicated (which are both directly related to creating eLearning). Also, for this particular portfolio, I included a CD at the end with several examples of my courses. It's a great takeaway for the employer after the interview.
I'd be happy to send you the entire thing separately (it contains images of my work from my previous employer, so I don't want to post it here). Even if you wanted, I have several extras and would be happy to send you a physical copy.
Let me know!
eLearning Project Portfolio NEW SIZE.pdf