For some reason I am incapable of remembering that it's lift:embed and not lift:include, so I'm writing it down. Along the same lines, I can never remember how to change the evaluation order of a snippet call (is it even called a 'snippet call'?). Examples follow.
Embedding a fragment of HTML in a template
<lift:embed what="path/to/fragment"/> <!-- DO NOT add .html to the what= part what= is relative to src/main/webapp in source tree -->
Embedding a fragment of HTML containing lift bindings in a template
<lift:MySnippet.foo eager_eval="true"> <lift:embed what="path/to/fragment_with_bindings"/> </lift:MySnippet.foo>