Everyone probably knows this, but just in case you're dense like me and find yourself creating a CS mod just to prepopulate your comment Url field so you don't have to enter it over and over and over again to respond to your friends comments, STOP!
[Geez this is embarrassing, but because I care so darn much, I'll expose my own dweebness to dispel CS darkness with the light...]
This URL is populated from the CurrentUser.Profile.Weblog address for any registered site user. I know, as owners of our blog, and particularly on a single-user blog, we don't think of our Profile settings. But this is where the URL field comes from, so if you enter it here you will never have to enter it ever again. Ever.
Rediscover the joy in replying to comments again. Just don't tell anyone you didn't know you could auto-fill your URL by entering your Blog address in your profile.