Two free great tools which I use:
Watching rankings is a waste of time. Rankings tell you nothing. Just because you rank number one for a keyword or phrase doesn't mean anything. Capture more useful data/ insights, such as what keywords are driving traffic to your site or do some keyword research and identify keywords in which you want to capture a lot of traffic from and monitor those results. At the end of the day you want more traffic to your site.
Plus with Google's personalized search it is tough to see what each individual user is seeing, each SERP will be different.
If you are looking for keyword / keyphrase ranker, digital points Keyword Tracker & Keyword Ranking Tool is pretty good - and its free. Not pretty, doesn't give advice - but good for gathering data.
http://dccheck.com/ is good to check the datacenter ranking differences between google sites.
http://www.googlerankings.com/index.php is good to do a site / keyword comparison - deals with allinurl's , etc.
Google Toolbar shows you Google's page rank
I used to use WebCEO who i believe still offer a free version of the software. For comprehensiveness i would recommend them, but nowadays i'd prefer to use a SAAS (hosted) solution such as SEOmoz.
WebCEO also offer a free SEO University to help make sure you understand all of the basics.
You can get the Alexa toolbar (http://www.alexa.com/toolbar) for your browser. That will give you instant information about the traffic rank and evolution.
You can use also take a look at the Grader tools that HubSpot makes available for free (http://grader.com/). You have a Web Grader, a Blog Grader. These give you a good report on how your rate in SEO terms.
Hope this helps
Most of these are amateurish rank trackers. I would recommend RavenTools (monthly) or the fantastic Market Samurai (desktop). You can try 100s-1,000s of keywords instead of 1-10 at a time.