Floor mats

[Industrial Toys]

I like something that is removable to let things dry out underneith occasionally.

 

[The Deerslayer]

I also used a stall mat from TSC with great results IMO. I fastened them down, but you could certainly use just the mat as it is heavy enough to stay in place and remove when desired. Here is a link to the thread that has some pics.
I also added a piece to the center hump for additional coverage. That piece is attached with heavy duty velcro as I did not want to drill into the metal. http://www.tractorbynet.com/forums/kubota-owning-operating/337995-l3901-deck-mats.html?highlight=

The whole set up has worked extremely well for me and it provides a no-slip surface that is easily cleaned.