NOTE: I created a crude version of this page for my own reference, after having to look these options up one too many times, and then stumbled on Mat's version: http://www.asquare.net/gwt/usage.jsp - afterwards I cleaned up my own version into this page - just in case any other stumblers find this.

JavaDocs

JavaDocs - GWT 1.4.60

GWTShell

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar com.google.gwt.dev.GWTShell -help

Google Web Toolkit 1.4.60
GWTShell [-port port-number] [-noserver] [-whitelist whitelist-string] 
[-blacklist blacklist-string] [-logLevel level] [-gen dir] [-out dir] [-style style] [url]

where 
  -port       Runs an embedded Tomcat instance on the specified port (defaults to 8888)
  -noserver   Prevents the embedded Tomcat server from running, even if a port is specified
  -whitelist  Allows the user to browse URLS that match the specified regexes 
(comma or space separated)
  -blacklist  Prevents the user browsing URLS that match the specified regexes 
(comma or space separated)
  -logLevel   The level of logging detail: ERROR, WARN, INFO, TRACE, DEBUG, SPAM, or ALL
  -gen        The directory into which generated files will be written for review
  -out        The directory to write output files into (defaults to current)
  -style      Script output style: OBF[USCATED], PRETTY, or DETAILED (defaults to OBF)
and 
  url         Automatically launches the specified URL

JUnitShell

OBTAIN: Create and run a GWTTestCase with the system property -Dgwt.args="-help" set.

Google Web Toolkit 1.4.60
JUnitShell [-port port-number] [-whitelist whitelist-string] [-blacklist blacklist-string] 
[-logLevel level] [-gen dir] [-out dir] [-style style] [-web] [-notHeadless]

where 
  -port         Runs an embedded Tomcat instance on the specified port (defaults to 8888)
  -whitelist    Allows the user to browse URLS that match the specified regexes 
(comma or space separated)
  -blacklist    Prevents the user browsing URLS that match the specified regexes
 (comma or space separated)
  -logLevel     The level of logging detail: ERROR, WARN, INFO, TRACE, DEBUG, SPAM, or ALL
  -gen          The directory into which generated files will be written for review
  -out          The directory to write output files into (defaults to current)
  -style        Script output style: OBF[USCATED], PRETTY, or DETAILED (defaults to OBF)
  -web          Causes your test to run in web (compiled) mode (defaults to hosted mode)
  -notHeadless  Causes the log window and browser windows to be displayed; 
useful for debugging

GWTCompiler

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar com.google.gwt.dev.GWTCompiler -help

Google Web Toolkit 1.4.60
GWTCompiler [-logLevel level] [-gen dir] [-out dir] [-treeLogger] [-style style] module 

where 
  -logLevel    The level of logging detail: ERROR, WARN, INFO, TRACE, DEBUG, SPAM, or ALL
  -gen         The directory into which generated files will be written for review
  -out         The directory to write output files into (defaults to current)
  -treeLogger  Logs output in a graphical tree view
  -style       Script output style: OBF[USCATED], PRETTY, or DETAILED (defaults to OBF)
and 
  module       Specifies the name of the module to compile

ApplicationCreator

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar:$GWT_HOME/gwt-user.jar com.google.gwt.user.tools.ApplicationCreator -help

Google Web Toolkit 1.4.60
ApplicationCreator [-eclipse projectName] [-out dir] [-overwrite] 
[-ignore] className 

where 
  -eclipse    Creates a debug launch config for the named eclipse project
  -out        The directory to write output files into (defaults to current)
  -overwrite  Overwrite any existing files
  -ignore     Ignore any existing files; do not overwrite
and 
  className   The fully-qualified name of the application class to create

ProjectCreator

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar:$GWT_HOME/gwt-user.jar com.google.gwt.user.tools.ProjectCreator -help

Google Web Toolkit 1.4.60
ProjectCreator [-ant projectName] [-eclipse projectName] [-out dir] 
[-overwrite] [-ignore]
where 
  -ant        Generate an Ant buildfile to compile source (.ant.xml will be appended)
  -eclipse    Generate an eclipse project
  -out        The directory to write output files into (defaults to current)
  -overwrite  Overwrite any existing files
  -ignore     Ignore any existing files; do not overwrite

JUnitCreator

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar:$GWT_HOME/gwt-user.jar com.google.gwt.junit.tools.JUnitCreator -help

Google Web Toolkit 1.4.60
JUnitCreator -junit pathToJUnitJar -module moduleName [-eclipse projectName] 
[-out dir] [-overwrite] [-ignore] className 

where 
  -junit      Specify the path to your junit.jar (required)
  -module     Specify the name of the GWT module to use (required)
  -eclipse    Creates a debug launch config for the named eclipse project
  -out        The directory to write output files into (defaults to current)
  -overwrite  Overwrite any existing files
  -ignore     Ignore any existing files; do not overwrite
and 
  className   The fully-qualified name of the test class to create

I18NCreator

OBTAIN: java -XstartOnFirstThread -cp $GWT_HOME/gwt-dev-mac.jar:$GWT_HOME/gwt-user.jar com.google.gwt.i18n.tools.I18NCreator -help

Google Web Toolkit 1.4.60
I18NCreator [-eclipse projectName] [-out dir] [-overwrite] [-createMessages] [-ignore] interfaceName 

where 
  -eclipse         Creates a i18n update launch config for the named eclipse project
  -out             The directory to write output files into (defaults to current)
  -overwrite       Overwrite any existing files
  -createMessages  Create scripts for a Messages interface rather than a Constants one
  -ignore          Ignore any existing files; do not overwrite
and 
  interfaceName    The fully qualified name of the interface to create