One of the missing elements in lead generation is having a good lead capture tool.
One of the ways I judge if a client is ready to take lead generation seriously is by looking at the lead capture tool they are using.
The best case scenario is when someone has integrated their lead generation right into the full sales process and the leads that come in from the web go straight to sales people that are ready to follow up.
If you are not that big yet, then you should be using an autoresponder to capture leads and automatically follow up with the prospect.
Here some some tools worth taking a look at.
There are many more options depending on what you are trying to do, but you do have to have a good set of lead capture tools that will make sure you do not let the valuable leads slip through the cracks.