You may of course use whatever format works best for your department, but the most widely accepted format for preplans is NFPA 1620.  (The Academy Library has it and a separate NFPA CD of fire and life safety CAD symbols.)  Jenaway’s  “Pre-emergency planning: a guidebook for fire service officers to prepare for and manage emergency situations” book is also quite good.  Another noteworthy book/CD you could consider is Vulpitta’s “On-site emergency response planning guide: for office, manufacturing & industrial operations”.  All the above may be borrowed from the Accademy Library.   You may also want to look at https://erplan.net/eplan/login.htm if dealing with sites that have hazmat.

The USA Branch of the Institution of Fire Engineers "Vision 20/20" program has a useful "Community Risk Assessment Guide" http://riskassessment.strategicfire.org/  to help fire departments and other organizations to conduct a basic or more complex assessment of risks within their community. Ultimately, the results of the risk assessment can be used to develop a CRA plan. 

OSHA's current approach for specific occupancies or buildings is a "Evacuation Plans and Procedures E-Tool" at https://www.osha.gov/SLTC/etools/evacuation/index.html .  

OSHA's former free software program called "Fire Safety Advisor"  http://www.osha.gov/dts/osta/oshasoft/softfirex.html (last version is 2000) was useful for preplanning a specific occupancy.  For those who would like to compare it to the new version, "Fire Safety Advisor" may still be downloaded at http://web.archive.org/web/20140102181051/https://www.osha.gov/dts/osta/oshasoft/softfirex.html  .

Form examples:

http://www.deltafire.ca/PDFs/Website%20Business%20Forms/Fire%20Preplan%20Blank%20Template.pdf
http://www.henrycoema.org/forms/FDPreplanTemplate.pdf
http://www.snocountychiefs.org/documents/50-01-11_pre_incident_planning.pdf (mostly appendix at end)
http://westridgefire.org/PrePlanFormSubmit.pdf
http://www.usfa.fema.gov/pdf/efop/efo38130.pdf 
http://sugarcreekfd.clubspaces.com/object.aspx?id=11&o=227658
http://www.kingsvillefire.ca/Pre-plan_Form.pdf
http://www.clevelandfd.com/preplan.pdf

http://www.templeterrace.com/fire/pdfs/SOG/Forms/Prevention%20and%20Special%20Programs/Form%202.2.3%20Pre-Fire%20Plan.pdf

There's an App for that! (for smartphones, IPads, etc.)

Occupancy by Emergency Reporting http://www.emergencyreporting.com/mobile/index.html 

http://www.extinguishapp.com

AID Fire Preplan II https://play.google.com/store/apps/details?id=com.fossworking.AID_FirePreplanII 

PreplanSource http://www.preplansource.com/ 

For farms & agricultural occupancies:
http://www.hoards.com/sites/default/files/DE_farm_fire_preplan.pdf
http://ipm.ncsu.edu/pesticidesafety/PrePlan.pdf

There is also commercial software  designed to help with this, for example:

Firehouse Software http://www.firehousesoftware.com/products/fh-mobile/preplans.php

FirePrograms http://www.fireprograms.com/risk-manager.html

FireZone  http://www.cadzone.com/fire-service-diagrams and  http://www.cadzone.com/mobile-pre-plans )

FDM Software  http://www.fdmsoft.com 

MobileEyes http://www.mobile-eyes.org/MKTG_PlanAndRespond.asp?gclid=CNu16cOR8rUCFWfNOgodO2cAlw

If you're interested in digitizing your old paper preplans, you'll to consider the tradeoffs between simply scanning old paper documents and creating new “born digital” plans.  Although OCR scanning might be able to convert scanned material to editable documents, there will be read errors which need to be resolved by a human.  Also, “born digital” information can be used and accessed in a variety of different ways – for example, see http://finepointwriting.com/wp-content/uploads/2011/03/NewAge_PrePlans_Final_RevC041410.pdf.

Keeping in mind that grant money is getting tight, some FDs have received NYS grants in the past for digitization projects.  See http://www.archives.nysed.gov/a/grants/grants_lgrmif.shtml for more info.  There’s a story at http://www.firehouse.com/node/41261 which gives an example.  The Archives people may be able to refer you to specific vendors.