It depends on what your site is, i would of thought that is quite obvious, for example if you was a sad git visiting a train spotting site then i presume people might like to read all about errrrr trains, in depth write ups, where it was last spotted etc.
If you are running a porn site then i would equally guess that people might actually like to see some real hardcore betty sweaty action.
And if you are running a forum i guess people might like to read other peoples posts and related info.
It depends what you want to do dunnit! easiest was is to think, if i was joe bloggs and i was to visit my site what would he or she like to see, then you need to take a step back and say ok thats what they would like to see and then how can i make money out of it.
For me i give them enough information to get them started but make sure they visit the merchants site to get any extra or missing information because if i tell them too much they never leave the site to buy anything as the more information you give people sometimes the more questions they have, especially if they are trainspotters.
EDIT: No direct offence to train spotters, if you like dressing up in cagools or however you spell them and earting packed lunch out of tupperware and having a nice old thermos down at the local railway track then thats just fine and dandy, though a tad silly if you ask me. But like you dont bother me when i
am watching porn, i will not bother you while you are watching trains........ trains/porn...trains/porn...god its hard to choose between them....