You might be knowing about some of these hidden applications in Windows XP but definately not all of them.
To run any of these apps go to Start > Run and type the executable name :
1) Character Map = charmap.exe (very useful for finding unusual characters)
2) Disk Cleanup = cleanmgr.exe
3) Clipboard Viewer = clipbrd.exe (views contents of Windows clipboard)
4) Dr Watson = drwtsn32.exe (Troubleshooting tool)
5) DirectX diagnosis = dxdiag.exe (Diagnose & test DirectX, video & sound cards)
6) Private character editor = eudcedit.exe (allows creation or modification of characters)
7) IExpress Wizard = iexpress.exe (Create self-extracting / self-installing package)
8 Microsoft Synchronization Manager = mobsync.exe (appears to allow synchronization of files on the network for when working offline. Apparently undocumented).
9) Windows Media Player 5.1 = mplay32.exe (Retro version of Media Player, very basic).
10) ODBC Data Source Administrator = odbcad32.exe (something to do with databases)
11) Object Packager = packager.exe (to do with packaging objects for insertion in files, appears to have comprehensive help files).
12) System Monitor = perfmon.exe (very useful, highly configurable tool, tells you everything you ever wanted to know about any aspect of PC performance, for uber-geeks only )
13) Program Manager = progman.exe (Legacy Windows 3.x desktop shell).
14) Remote Access phone book = rasphone.exe (documentation is virtually non-existant).
15) Registry Editor = regedt32.exe [also regedit.exe] (for hacking the Windows Registry).
16) Network shared folder wizard = shrpubw.exe (creates shared folders on network).
17) File siganture verification tool = sigverif.exe
18 Volume Contro = sndvol32.exe (I've included this for those people that lose it from the System Notification area).
19) System Configuration Editor = sysedit.exe (modify System.ini & Win.ini just like in Win98! ).
20) Syskey = syskey.exe (Secures XP Account database - use with care, it's virtually undocumented but it appears to encrypt all passwords, I'm not sure of the full implications).
21) Microsoft Telnet Client = telnet.exe
22) Driver Verifier Manager = verifier.exe (seems to be a utility for monitoring the actions of drivers, might be useful for people having driver problems. Undocumented).
23) Windows for Workgroups Chat = winchat.exe (appears to be an old NT utility to allow chat sessions over a LAN, help files available).