You can search for patents that are similiar to the one you found by looking at the Current U.S. Class, Current International Class (if you were going to do an international patent search), and Field of Search.
The Current U.S. Class search show you what classifications this patent is filed under.
The Field of Search are similar classifications that a Patent Officer searched under.
These fields are good for expanding your search and finding classifications you may have missed.
If your patent has a Referenced By hyperlink, click on it! Chances are you may find patents which may have a newer variation of the patent you are viewing.
You may also be curious to view other older variations of the patent you're currently viewing. You can find those patents under the References Cited and access them by clicking on the patent number hyperlink.