For unreal physics: pretty much every space battle in David Weber's "Honor Harrington" series. The tactics used are often pretty creative (or certainly seemed so on a first reading).

For slightly-closer-to-reality: the space battle in Niven's Protector. Although, I must confess this is nowhere near as creative as some of what has been described in this thread.

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The quarrelsome oarsmen were rowing,
The great violinist was bowing;
But how is the sage
To tell, from the page:
Was it pigs or seeds that were sowing?