I have just downloaded the Google Desktop Search 2.0 Beta, I quite like it. I would like to be able to force it to index when not Idle, but thats the only complaint so far.
I am looking forward to being able to search for things amazingly quickly, I have held off from using others because they took up lots of resources on my pitifully weak machine. This one seems to be pretty good though.
I have installed an Adsense plugin to see how much revenue I don't get from this blog. ;)
I like the Gmail plugin that comes as standard, and the feed detection is really really good. It beats Internet Explorer (IE7 Beta 1) hands down. It shows a very simple outline of all the blog entries that I am interested in. It doesn't allow any aggregation of any sort, so it is more of a news bulletin system. Its pretty cool though.
I will post more opinions once I have played with it a bit more.