I have previously documented:

<a href="/article/jsifaq/jsi-tip-4403-how-do-i-disable-the-windows-xp-balloon-tips-.aspx">How do I disable the Windows XP balloon tips?<p>

<a href="/article/jsifaq/jsi-tip-9376-how-can-i-disable-some-start-balloon-menu-tips-.aspx">How can I disable some Start Menu Balloon tips?</a></p>
<p>

<a href="/article/jsifaq/jsi-tip-4451-how-do-i-suppress-the-windows-tour-prompt-in-windows-xp-.aspx">How do I suppress the Windows Tour prompt in Windows XP?</a></p>
<p>

<a href="/article/jsifaq/jsi-tip-5944-how-do-i-configure-the-highlight-newly-installed-programs-option-via-the-windows-xp-registry-.aspx">How do I configure the 'Highlight newly installed programs' option via the Windows XP registry?</a></p></a>

Here are a few more:

To disable <b>Start</b> button balloon tips:  

    <b>REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V StartButtonBalloonTip /T REG_DWORD /F /D 0</b>

To disable folder content information bubbles:

    <b>REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V FolderContentsInfoTip /T REG_DWORD /F /D 0</b>

To disable popup descriptions for icons and folders:

    <b>REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V ShowInfoTip /T REG_DWORD /F /D 0</b>

To disable reminder balloons above the Offline Files icon in the notification area:

    <b>REG ADD "HKCU\Software\Policies\Microsoft\Windows\NetCache" /V NoReminders /T REG_DWORD /F /D 1</b>

To disable the reminder to apply for a Microsoft Passport:

    <b>REG ADD "HKCU\Software\Microsoft\MessengerService" /V PassportBalloon /T REG_BINARY /F /D 0a000000</b>