Slideshare is a site created for sharing slideshow presentations.
It allows uploading, downloading, embedding, emailing and viewing thousands of slideshow presentations. To start using it, you only have to sing up and create an account. Since that moment you can start uploading your presentations to have them ready for embedding or sharing.
A very important characteristica of Slideshare is that it allows the tagging of presentations, so that they can be easily found. You can search by username or tags.
As an example, all the presentations published in this blog have been previously uploaded in Slideshare. I do not only use it as a way to embed, but as a safe place to have all my presentations available from everywhere and by everyone.