How can I see the list of connected players?

Press TAB, then you will see who is online on the server. To change the button binding for this, press ESC and go to Controls.

This command is only available to ops. Only commands /kill, /me and /tell can be executed by non-ops.

I run a bukkit server and I let the players use the /list command. Even though you can push tab its nice to have a number and list of names right there in your chat box.

You can regulate the commands a player can use depending on the command plugin you use. I use the Essentials command pack.

You can bind the key in the options menu:

ESC > Options > Controls > List Players

Windows: Bind it to TAB.

Mac: Bind it to CMD.