Can snippets be created/managed via the API?

No, we do not have APIs to let you create snippets.  However, we would love to know more about the use-case and how you would use them if they are available

Compendium is the largest content marketing platform and we're building a Marketo integration. We use snippet-like functionality to integrate with Eloqua, allowing clients to distribute content into snippets for use in emails and landing page.

James,
We are on the cusp of releasing an email scripting feature which will allow you to customize emails.  APIs to create snippets is a backlog item which we will get to only next year.

Raj