There are two thumbnails in this gallery. The original picture was taken by a company photographer using an expensive Kodak camera minus the AA filter; he chose to leave the AA filter off to get as much resolution as possible for the group shots during an important company function.
The first thumbnail is a 100% crop from the original and demonstrates why an AA filter "in front the sensor" is an important design feature (note, the aliasing error caused low frequency artifacts that have totally ruined a portion of the four-person group picture).
A second thumbnail is provided to show additional sampling artifacts you can incur while down-sampling a picture to a lower resolution for subsequent web presentations. Note how much worse the artifacts are if you don't down sample by "factors of two."
Why an AA filter is required (original @ 100%)
Additional artifacts due to down-sampling (i.e. resizing)