This may not be exactly what you are looking for as I suspect you are mainly looking for information for children, but here’s some quick Vit K info from more of a technical standpoint (I covered some Vit K info in my research):

3 types of Vitamin K:
K1 (phylloquinone): Mainly controls blood coagulation.
K2 (menaquinones (MK-4 (menatetrenone) through MK-10)): Help control calcium uptake in bones & controls calcium levels in bloodstream (via osteocalcin, etc. carboxylation).
K3 (menadione): Synthetic and generally not recommended for supplementation.

Some good Vit K links (general info):
http://www.lef.org/magazine/mag2000/feb00-report.html
http://www.lef.org/magazine/mag2004/mar2004_aas_01.htm
http://www.lef.org/magazine/mag2002/...t_vitk_01.html
http://www.pdrhealth.com/drug_info/n...vit_0267.shtml
http://en.wikipedia.org/wiki/Vitamin_K

Some good research studies (Medline/PubMed, full text documents are available for these). Vit K2 appears to do a very good job with bone health (osteoporosis) and alleviating arteriosclerosis:
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum

Lots of additional research is currently being performed with Vit K. From what I gather, it appears that adequate Vitamin D (but not overdoing it) is needed for appropriate calcium absorption, and then Vitamin K (K2) puts calcium where it needs to be… in the bones.

P.S.
A suggestion for this forum might be to have specific threads dedicated to technical/research/reference information for each vitamin/nutrient. Threads could be labeled, for example, “Vitamin K, Research Data” or “Vitamin K, Reference Information” and appropriate links to research/reference documents, etc. could be posted in these threads. We could still keep the “Useful Websites” sticky reserved for overall reference databases/knowledgebases (for ex. drug-vitamin/nutrient depletion references, etc.). Perhaps this will help keep the information organized. Any thoughts?