the_content into a variable

Inside an already severly customised Loop, I want to use the_excerpt to show the excrpt but want to also parse the content that would normally be displayed by the_content with php for some special customisation, e.g. show a reduced version of the first image in the post. Is this at all do-able? (as a quick php hack) or would something like this require creating a whole plugin?

T.I.A.