You can play "Peggle" online either at the MSN Zone website or with YouPlay. However, each requires specific browser settings or additional plugins in order to work properly.
The easiest way to play "Peggle" is to download it directly from the PopCap Games website or Pogo, but because it is a download, it requires the installation of files. Additionally, the only free downloadable version available of "Peggle" is a 60-minute trial, after which players must upgrade to the full paid version in order to continue playing.
There are games similar to "Peggle" that are available for free, such as "Polinko" at Plonga, but these are generally simpler versions that lack the level of polish and number of features found in the original "Peggle" game.