Some of the things to consider including in an observation

-Your name and email address
-Date/Time
-Location (description of where, GPS coordinates if possible) including aspect, 
               slope, elevation - alpine/tree line/below tree line?)
-Any Red Flags?
     -Recent avalanche activity

     -Whumphing noises, shooting cracks, or collapsing
     -Recent loading by new snow, wind, or rain
     -Rapid warming
     -Obvious avalanche path
     -Terrain Trap
-Snowpack observations:
     -You can get alot of information without digging a pit
        -What did you see?  Wind Loading?  Layers felt through ski pole? 
     -Pit data (description or profile)
     -Test results (pit tests, ski cut tests, cornice drop, skiied slope?)
     -What do you think? 
-Avalanche Observations:
     -Type (soft slab, hard slab, loose, wet)
     -Trigger (human, natural)  
     -Slope, Aspect, Elevation
     -Bedsurface, Weak Layer, Crown Ht, Width, Length
     -Above/below treeline
     -Anyone caught/injured/worse?
       click here for a link to a full guide to character description of avalanches
-Weather
     -Aprox Temp, Winds(dir, strength), Sun/clouds, Precipitation.

Photos are great, as are videos!

-As a bonus tell how the skiing/boarding/snowmo-ing conditions were!

For some more examples of profesional and public submitted observations check out:
http://www.sierraavalanchecenter.org/observations