Wow, this was a tough one. I would hate to wake up tomorrow and be told one or the other didn't exist (*shudder*). But here's the thing: while Excel is really nice, I could plug the gap with other tools. It's convienent, and makes things easier, but I could conceivably do my job just as well without it.
Webmail, though? A communication job without email? Sure, we could go back to the days of phone trees (easier now with cell phones) and actual mail, but the document sharing capabilities of webmail can not be beat. Sending out announcements to the entire production without email just fills me with horror. I don't think there is a true substitute for email. It is an indispensable tool of the world we live in.
All that being said, I'm very happy to have my spreadsheets as I prep paperwork for my next show.