I usually check the appshopper.com for apps every night that I may want... this site has added some new things to it to help you keep track of what apps you want and own and ones you want to add to your wish list...

Also whats really neat is they will keep you up to date on your apps through email as well... I wish itunes would at least let us have a wish list! As for keeping you up to date on your apps itunes does that for you if you check your applications updates often....

The most important part that I like is the wish list... that way I can keep track of ones I might want at a later time...