Here are few that I uploaded....

Macro /w Extension Tube by khurramaziz, on Flickr
Exposure: 1/60 @ f/8.0
Focal Length: 50mm
ISO: 100

Macro /w Extension Tube by khurramaziz, on Flickr
Exposure: 1/60 @ f/9.0
Focal Length: 50mm
ISO: 1600

Macro /w Extension Tube by khurramaziz, on Flickr
Exposure: 1/60 @ f/22.0
Focal Length: 50mm
ISO: 1600
The free Flickr account got filled; havnt decided yet what to do next :-#
Kenko / Extension Tube; just like 50mm f/1.8 is nifty little thing; I would say its better than Teleside Close Up Lenses / Filters like Raynox; gives better results and comparatively easier to install...Obviously you cannot compare such budget approaches with any Macro Lens 
If no near future plans for "full frame goodness" then do consider the EFS-60mm Macro; it should serve the both purpose. I could not find its "opened" / trial copy at any local outlet (A) to get its feel