I'm trying to figure out the best way to track how keywords rank in organic search over time as I continue to optimize the site. Analytics doesn't seem to do a very good job of trending, but I haven't heard of anything else filling the gap either. What do you use to measure the efficacy of your SEO changes? Thanks!
there are many tools available out there to do so but i do it manually as it helps to comprehensively cover every aspect.
Its simple: traffic. If you are getting more traffic based off different keywords than you will be able to see what is working and what isn't.
teenwolf41 hit the nail on the head, so using any traffic metrics tool, such as Google Analytics, Stat Counter, or even AwStats will give you a good idea of how you have progressed since point x.
for actual keyword rankings i use the free version of Web CEO. Its accurate and also shows you the change in ranking since the last check and produces good reports for you to record so you can track it over time. Apart from that i agree with the others, traffic is a perfect way to check trending and the effectiveness of SEO and marketing. Keep an eye on your Alexa rank to see if its headed in the right direction.