My latest beta of Quicksilver (QS) crashed while I was in Safari, and I kept hammering down on the Command-Space key combo (my setting to activate QS, not Spotlight) before I realized this. The QS dialog did not appear, but what I did notice was that new tabs were appearing in my Safari Tab row.
For this to work, the focus must be in the location bar (mouse click somewhere in the address area, or hit Command-L), and you can't have Command-Space assigned to any other function. Type Command-Space and watch a new tab appear with the same page as the current tab. This also works when there are no tabs open on screen.
I haven't seen this hint before, so I'm hoping it's a new one.
[robg adds: This only works in 10.4, which seems odd -- why add a new feature that's assigned to a keyboard shortcut that's owned by Spotlight? I think that few people change their Spotlight shortcut, which is what you'll need to do if you want to use this trick.]

