I very rarely get a "Holy Shit" feeling. I get "Oh, that's clever" or "that's neat" quite a lot though. I think perhaps the fact I'm young so take things for granted and the fact nowadays I see everything as it appears on the internet makes everything seem more like a progression rather than shocking.

I do remember visiting Google Suggest and later Google Maps and being very impressed and knowing it would change the web - until that point JavaScript has largely been seen as a toy. Gmail also really changed the landscape when it came out too.

The first time I used Opera's tabs in 2000 wasn't "holy shit" as much as a "well, that makes perfect sense" moment which are even rarer.