For one of my recent pieces of work I used some statistics from the NHS choices website on how effective contraception they were.
Snippet from my work -
The IUD prevents pregnancy at an effectiveness of 98-99% (NHS Choices, 2009) by preventing your partner’s sperm from getting through your womb and into your tubes, alter the secretions (mucus) in your cervix by releasing copper into your body, creating a further barrier for sperm.
I have referenced within text by using the publisher (NHS Choices) and the publication date (2009). It is hard to use authors name for when you are referencing websites as a LOT of material doesn't state a author, so state the publisher.
The above reference would look like this in my reference list, even if you paraphrase the information it still needs to be written in the reference list -
NHS Choices. 2009. Intrauterine Device - Introduction. [online] (Updated 01 Oct 2009) Available at: http://www.nhs.uk/conditions/Intrauteri ... ction.aspx [Accessed 13 Oct 2010]
Now the bibilography is made up of resources that you have READ but not used within your essay, this shows that you have done background reading and research into the topic for a better understanding.
So my biblography list for the above topic looks like this (just a snippet) -
FPQ. 2010. The contraceptive implant – Implanon. [online] Available at: http://www.fpq.com.au/pdf/Fs_Implanon.pdf [Accessed 13 Oct 2010]
Implanon. 2009. Things to know about Implanon. [online] Available at: http://www.implanon.co.uk/siteuploads/I ... g_card.pdf [Accessed 13 Oct 2010]
Net Doctor. 2008. Condoms. [online] (Updated 30 Sept 2008) Available at: http://www.netdoctor.co.uk/sex_relation ... ondoms.htm [Accessed 13 Oct 2010]
The above websites I have read for information, but not actually used within my work.
With pictures I do the same with websites when referencing in text as they are usually taken from the website and normally don't have a specific author.
Also this website - http://libweb.anglia.ac.uk/referencing/harvard.htm is very good at finding out how to reference different materials as it gives examples and states what information needs to be within the reference. I use this website through out my course.
Hope that helps.
If you have anything to add then please do.