Common File Locations Accessible from SharePoint WSPs

Folder in 12 hive	Contains
\ISAPI\HELP\[LCID]	SharePoint help files. Deploy your own .chm files to this folder (or a localized subfolder)
\CONFIG	Web.config customizations
\ISAPI	SharePoint web services (deploy your custom web services here as well); maps to /_vti_bin
\Resources	Global .resx files accessed from custom features and site definitions
\TEMPLATE\CONTROLTEMPLATES	.Ascx user controls; maps to /_controltemplates
\TEMPLATE\FEATURES	Features, of course!
\TEMPLATE\LAYOUTS	Common site pages; maps to /_layouts
\TEMPLATE\IMAGES	Common site image files; maps to /_layouts/images
\TEMPLATE\SiteTemplates	All SharePoint site definitions; create a \xml to deploy your onet.xml custom site definition
\TEMPLATE\THEMES	All UI elements used in themes; clone an existing theme folder to create your own
\TEMPLATE\[LCID]\XML	Webtemp.xml files to define available site definitions; add an xml file here for your custom site definition
\TEMPLATE\ADMIN	Pages used by Central Admin; maps to /_admin
\ADMISAPI	Administration web services; maps to /_vti_adm