slipping clutch bad for tranny? i always thought it was ok, just no dumping the clutch

Slipping in excess is not good either. You want just enough slip to make a smooth getaway, with
 

just enough power to not stall until the clutch is fully engaged - at which point you can use your right foot as liberally as you want ;-)

slipping ...more specifics please?
 

If you are in a gear and step on the gas and your tach climbs and you don't move much more...then your clutch is shot.

When you start out...you should just ease the clutch a a little gas 2k-3k rpm...no more is needed day to day. This kind of slip is fine.

The true test of driving stick is to get the car moving without steping on the gas untill your foot os off the clutch...

Slipping the clutch will not hurt the tranny.
 

It will burn up the clutch plate and it can improve acceleration off the line substanially. The 0-60 time difference between the manual tranny and the Tip is almost entirely due to the ability of the manual to keep the engine RPMs high during the start but this kind of start is very hard on the clutch.