Some common dialogs.

GetOpenFileNameCreates an Open dialog box that lets the user specify the drive, directory, and the name of a file or set of files to be opened.
GetSaveFileNameCreates a Save dialog box that lets the user specify the drive, directory, and name of a file to save.
MessageBoxExCreates, displays, and operates a message box. The message box contains application-defined message text and title, any icon, and any combination of predefined push buttons.
SHBrowseFolderDisplays a dialog box that enables the user to select a Shell folder.