hoya and vitacon has macro filter sets of 4 - +1,+2,+3,+4
you can use them individually or stack them for +10
they can be bought individually as well, there are also +10 filters
I'm sure there are other brands like tiffen and kenko
stacking in this order - camera>macro filter>wide-conv will take you even closer , but at the expense of DOF
there are a few older threads on Macro here in this section as well that are good references...
PS a mistake that i only learnt to rectify after reading up in CS - disable Macro Mode when you use a filter