On LinkedIn many users say that they cannot message people that request to connect, so generally accept the request.
What many people do not realise is that you can message them.
Here is a piece that many help you communicate with people requesting to connect without you actually accepting the connection first.
I would also always advocate looking at their profile to see if you could have met etc in the past
How to communicate without connecting
Just go to http://www.linkedin.com/inbox/invitations/pending and in the “accept” box there is a small arrow to the right, if you click on this it allows you to message them without accepting
You do not have to accept a request to connect in order to communicate with someone.
The power of LinkedIn groups
One of the little know facts seems to be that you can message people you are not connected to, if you are in a group they are in, assuming that is that they have not set the privacy options too high.
Collecting connections is follow and undermines the real value of the platform.