Here are some of the absolutely best articles I have come across of the years with regards to building and optimizing great landing pages and the calls to action (CTAs) that great pages need.

In no particular order:

• ClickZ “The Backward Landing Page” – I love this post!
• Landing Page Rehab by Oli Gardner
• Five Defining Features of Landing Pages 3.0 by Scott Brinker
• Ron Jones, ClickZ – AdWords Quality Scores depending on your landing page
• Case Study in Landing Page Optimization
• 13 Sloppy Mistakes You’re Making With Your Calls to Action
• SEOMoz – basic optimization strategy
• Alex Cohen – Search Engine Watch (paid search optimization)
• Oli Gardner – Traffic Optimization
• HubSpot – 10 Landing Page Optimization Points
• Kathy Long – Conversion SEO – 4 Tips
• Tim Ash – Landing Page Layout Principles

And, if the above pages weren’t enough to get you going, the resource below is one of the most comprehensive and up-to-date analysis of create the VERY BEST FORMs for all types of situations:
Conversion Optimization: An In-depth Guide to Forms