iGoogle is the most common, especially if you have gmail.
HOWEVER, I did read about this on lifehacker the other day:
http://lifehacker.com/393837/five-best-start-pages
There is this website that I’ve never heard of, and all it is is a start page, it’s very clean, very cool, and you can put just about everything you could want. I’m considering changing mine (been google forever) , because this site is just so clean and well done.
http://www.netvibes.com
I highly recommend it, I messed with it the other day for a few minutes and just fell in love with it, easy to customize, no bloat crap that google has allowed that stupid users put in to mess with on their google home pages (kinda like facebook has gotten with the gagillions of dumb applications! ARG!)
anyways, netvibes. I recommend it!