I am currently using the Bukkit Server and a couple mods/plugins such as LocalShops, Craftbook, Iconomy, and so on.
However, far more interesting mods (in my opinion) are out there, and I have NO CLUE how to implement them.
Everyone seems to have explanations for how to install these mods in SSP or Singleplayer, and I have been completely unsuccessful in attempting to figure it out myself.
I understand Planes Mod currently does not support Bukkit. And I am willing to kill the Bukkit server and start a different one so long as similar mods to Localshops and Craftbook can be found for said new server.