Sorry, here's the link on flickr.

Here is a link that might be useful: Exterior of House

I'd suggest that you have a number of things to think about to start:
1. Do you want a transom window over the door?
2. Do you want a wood door or some other material?
3. Do you want a door and storm door that are consistent with the vintage of your home?
4. Do you want a stained door or painted/color door?
5. Do you know your budget?

Look at this link for Simpson doors. It's an upper end company, but they have great styles and their website is very user friendly.

If you have specific questions, ask away!

Here is a link that might be useful: simpson doors

I forgot - you can also go the salvage store route and get a true historic, vintage main door. In our experience, storm doors are hard to find thru salvage, but there are tons of main doors out there.