The NIST (National Institute of Standards and Technology ) USA released three documents recently, these are listed below:
|date||number||version||title of publication|
|2007-02||SP 800-45||2||Guidelines on Electronic Mail Security|
|2007-02||SP 800-94||final||Guide to Intrusion Detection and Prevention Systems (IDPS)|
|2007-02||SP 800-97||final||Establishing Wireless Robust Security Networks: A Guide to IEEE 802.11i|
Having a look at the above three guides is definitely worth your time.
For instance, the IDPS document explains concepts used with very good examples that illustrate the points made very well.
It is also interesting to see how the three documents above relate and refer to each other. To illustrate Guidelines on Electronic Mail Security refers to the IDPS document in several places.
There is also nice information to be found about WLANs.
So even if you choose to glance over them only, you should look at the table of contents of each. This way you can select what you must read or want to read. Good reading.