I find that quite often I want to find a post on my blog. Because I often write about things I've found on the web the link to them is in my blog rather than my favorites folder. There are other things like in house Wikis or sharepoint sites where we want to go back to our own stuff- hence vanity searching. I find this is a great use of the search box in IE7.
I've added "My Blog" to the search list, and I'd pass that on as a top tip. Add search for any site you post to a lot. The easy way to do this is to search for the word TEST and then copy the URL from the address bar - if you paste it on on the "Search Providers" web page the server there will generate the open search XML that IE needs.
By the way in the screen shot on the right you'll see I've got Live Search as my default - I'm now finding it's quite rare that I have to drop back to Google. Once I've switched I'll keep on using Google until a search there doesn't work out. I've got a couple of other bits, Wikipedia (as you can see in the screen shot) is on my menu and while you're at the site it puts itself on the menu - that's what the yellow star is showing - the pull down menu also goes Orange when the site supports this - I really wish all Microsoft sites would - but like getting them changed to use silverlight, to write phone numbers as TEL: clickable links this seems a bit of a forlorn hope.