Although the inflections and compound-mania are largely absent from the English language, there are still some vestiges of its Germanic roots. One detail of English grammar that I often see neglected is the distinction between the verb+particle and the compound noun.
Consider the verb phrase "to shut down", which is the one I see misused most often. This is a verb+particle combination and is treated as two words. When you turn it into a noun, however, it becomes "shutdown", one word. This Knowledge Base article, for example, manages to keep its head on straight for most of the article, using the verb+particle for the verb form and the compound for the noun form:
\\computername: Use this switch to specify the remote computer to shut down.
/a: Use this switch to quit a shutdown operation.
But then it slips up towards the end and uses the compound as a verb:
To schedule the local computer to shutdown and restart at 10:00 P.M. ...
In other Germanic languages the distinction is clearer. Consider the Swedish and German verbs for "to make up" (as in, "to make up an alibi"):
In the verb+particle form, the particle comes after the verb, whereas in the single-word form, the particle comes before the verb. It's therefore more obvious when you have one word and when you have two. English does this only rarely, typically for verbs that retain poetic or archaic appeal ("cast down" → "downcast") and therefore reach back to the language's German roots for their power.
This is one of the reasons why I'm so fascinated by the Germanic languages: The more I learn about the other languages, the more I learn about my own.