Google Analytics. In particular, I'm interested in seeing if my bounce rate - the rate of visitors who arrive on the main page and then immediately depart from it - will improve if my full articles can only be accessed by clicking onto a derivative page.
My bounce rate, of course, is really not that important to me at this stage in the game. I'm not selling any product, and I have no ads on my blog with which to garner income, either. Technically speaking, my readership will probably be no different whether or not I have the 'Read more >>' function enabled, and my bounce rate will probably not differ other than to more accurately reflect who is actually reading. However, I'm interested - on the one hand - to know how many people are actually reading my posts - which can only be determined with complete accuracy by forcing a knowledge of how those 'bounces' actually break down - and - on the other - I'd like to improve my knowledge of how to create websites that thoroughly engage visitors.
By the way, if you have a website and you're not currently using Analytics, do it now. It's easy, and even if you don't use it in a 'hardcore' way, it's fun to look at the graphs - variously pies and lines - that show the action on your site, as well as the worldmap that shows where your hits are coming from (that's exactly what I've been doing until now). My objective with this new blog style is, in fact, to actually take full advantage of Analytics' capabilities, and make use of those capacities to determine the way my blog is experienced by readers, rather than just the raw numbers that are concerned.
Wish me luck!