Hey guys --
If you have a problem with Spatial Analyst appearing as a toolbar, but not in the ArcToolbox, try this solution (from the ESRI tech support):
Enable them for use in both ArcMap and ArcCatalog via the Tools menu > Extensions option.
Once you have enabled the extensions, please try the following to add the Spatial Analyst Tools to your ArcToolbox:
1. Launch either ArcMap or ArcCatalog
2. Right-click any area within ArcToolbox and select "Add Toolbox"
3. In the Add Toolbox dialog, select the "Look in" drop down and choose "Toolboxes"
4. Double click the "System Toolboxes" and add the "Spatial Analyst Tools" toolbox.
Hope this helps!