I don't know of a plugin that would make the Plugins menu two columns wide. That would be interesting but I'm not sure it could be accessed via Ruby anyway. You could edit some of the plugins to make them appear in other menus. Typically the menu in which the plugin will appear is show at the end of the .rb file and you could edit it in Notepad with no trouble.
Perhaps a better way would be to use the Sketchucation Plugin Store to manage your plugins. Surely there are some plugins you rarely use. Those could be set so they don't load normally and you can load them just when you want them. You could even create sets of plugins to load or not load as the need arises.