Nice. I am stealing this. I have the leader mapped to <Space>. And I move around splits and tabs using this.

    "New horizontal split
    nmap <leader>s :split<CR>

    "New vertical split
    nmap <leader>v :vsplit<CR>

    "New tab
    nmap <leader>t :tabe<CR>

    "Easy close
    nmap <leader>q :q<CR>

    " Split navigation
    nmap <leader>j <C-W>j
    nmap <leader>k <C-W>k
    nmap <leader>h <C-W>h
    nmap <leader>l <C-W>l

    "Tabs like Vimium 
    noremap <S-j> :tabprevious<CR>
    noremap <S-k> :tabnext<CR>