Here's a list of tools and utilities that are part of the Windows Installer SDK. Hopefully this short reference will help you find the right tool for the right job.

Orca.exe:
Allows you to open a Windows Installer database as a database and examine or make changes to it, for example with Notepad.

MSIFiler.exe:
Informs custom.doc to update the files around it.

WiFilVer.vbs:
Updates the file table sizes and version from source file tree. This is much like MSIFiler.exe.

MSITran.exe:
Generates or applies a transform file and can be used to view the transform file. Compares two databases (such as ms.db and custom.db) and generates the transform file.

MSIZap.exe:
Allows you to get Windows Installer back to a clean state. This support tool helps Windows Installer maintain the configuration data about all applications.
WiDiffDB.vbs Lists the differences between two databases (CSCRIPT only).

WiFeatur.vbs:
Lists features and their composition in an installation software database.

WiGenXfm.vbs:
Generates a transform from two databases, or compares them.

WiLstPrd.vbs:
Lists products, product properties, features, and components installed on a computer.

WiPolicy.vbs:
Manages installation software Group Policy settings (alternative to set policy).

WiUseXfm.vbs:
Applies a transform to an .msi database.