I know it existed as sort of a folder in Windows Explorer in at least Windows XP, but I just can't seem to find it in Windows 7...
How can I take a picture with my webcam in Windows 7 without using any 3rd party tools?
Answer I wrote from another similar question.
Technically it isn't built in, but it is by Microsoft - so hope that doesn't count as third party in your books.
I find the best and quickest program to be Microsoft AMcap.
It works via native DirectX functions and is very lightweight.
You can do that easily with an free online flash app: http://blog.chrometaphore.com/wp-content/uploads/2010/04/WebcamSnapshot.swf
(it's an example but you can found a lot)
An other example of an online photobooth (using HTML5, with Flash fallback), which require no additional software
The most straightforward way it to install Picasa ..: http://picasa.google.com/
.. click on icon for "Capture photos and videos from a webcam or other video device" ..:
.. and then take picture or record video:
For Lenovo users, there's the Web Conferencing tool that comes with your ThinkPad that allows you to save camera snapshots. I know it's not an answer to the original question, but I arrived here via a Google search for a quick way to take a snapshot with my built in webcam so I guess more people will.