I'm totally the other way round, anything serious I do on the PC is for the Amiga
Well apart from spending way too much time in browsers...
What's this hobby talk!? We're not talking about 'what do you use your Amiga for at work', right!?
Actually, I think the ratio of game vs. 'serious' use of computers in the evening is probably pretty even across the computer models...
But yes, word processing, database, spreadsheet is the area where Commodore Amigas are still decent ehm, editing machines. I don't know, are there decent webdev packages? Should be possible to make a decent Frontpage/DreamWeaver type editor for simple and useful webpages, at least.
PHP/MySQL/JS, dunno how tricky it is on Amiga, at least testing JS would be quite hard
And don't forget that not long ago all the university professors used far less capable machines for all their research, data processing and publishing. I bet they still thought they did serious work!