The New Action wizard allows you to uncheck both menu and toolbar placement for your action and only assign a keyboard shortcut. To learn how to do this manually, read on. Refer to TaT_HackingNetBeansXMLLayerPartOne for more details.
<folder name="Actions">
<folder name="Tools">
<file name="org-nvarun-tat-SayCheez.instance"/>
</folder>
</folder>
<folder name="Menu">
<folder name="Tools">
<file name="org-nvarun-tat-SayCheez.shadow">
<attr name="originalFile"
stringvalue="Actions/Tools/org-nvarun-tat-SayCheez.instance"/>
<attr name="position" intvalue="150"/>
</file>
</folder>
</folder>
<folder name="Toolbars">
<folder name="Build">
<file name="org-nvarun-tat-SayCheez.shadow">
<attr name="originalFile"
stringvalue="Actions/Tools/org-nvarun-tat-SayCheez.instance"/>
<attr name="position" intvalue="325"/>
</file>
</folder>
</folder>
<folder name="Shortcuts">
<file name="O-F3.shadow">
<attr name="originalFile"
stringvalue="Actions/Tools/org-nvarun-tat-SayCheez.instance"/>
</file>
</folder>
See also DevFaqKeybindings.
(Reposted from this entry on NetBeans Zone.)