Well, I am sure you have at least heard about Google Finance. I am very happy with this move. I have used Yahoo! Finance in the past, and it is alright, but I am partial to Google because I own it via a mutual fund, AGTHX. So, when it was announced that Google would be holding a live beta for Google Finance, I was excited.
From what I have read, there are many people who are complaining about a lack of features. However, you must remember that this is a beta, and it just started. I have already seen changes, just after my one day of using it. So far, Google Finance is better at everything it provides. I would expect nothing less. I noticed today that they added in news event to the stock graph, so that you can see what news events happened at what price point, and then you can try to measure what effect it had, if any.
As with everything that Google does, I am sure Google Finance will be extremely featureful, and highly polished. Give it a couple of months and I am sure it will be about as complete as necessary to make Yahoo! Finance irrelevant.
On a side note, I am a bit angry with Google because they cancelled my AdSense account. It happed one day after I posted about executive salaries, and I shed some light on the Google Execs compensation. Seems fishy. They said it was for possible click fraud... but I certainly know better than that.