A few people ride bikes to work - you can have a shower if you get a sweat up!
I've experienced problems getting taxis to take me from the terminal to the tower. They want to pick up a higher fare, say to Dandenong/Frankston. I've had some success going upstairs to the taxi drop-off at Departures and asking if they'll take me around to the tower. Since they are heading that way anyway, to the taxi rank, they'll often say ok.