Tech meetups: http://calagator.org/
Retro arcade: Ground Kontrol
Nature: 10 zillion wonderful beautiful waterfalls and hikes nearby, I recommend a place called Angel's Rest for starters.
Coffee: Crema, Extracto, Stumptown
Tea: Townshend's Tea House, Tea Zone, Tao of Tea
Food: Pambiche, Pine State Biscuits, Tin Shed, Screen Door, ... there are too many to list, really. Epic food all over.
Dessert: Sahagun Chocolates, Cacao, Rimsky-Korsakoffee, Pambiche again
Employment: GOOD LUCK... Portland is already oversaturated with talent.
The main Powell's location is just as much a destination as the Technical Books store and the two locations are just a couple blocks apart.
Portland's public wi-fi project has never seemed to work very well for me. I don't know if they've improved it recently, but kudos to the city for at least trying.
Rimsky-Korsakoffee is quirky and clever with mechanical secrets built into the furniture, and also really good desserts and coffee.
Radio Cab is one of my favorite cab companies anywhere I've traveled, but in Portland you always have to call the dispatcher to get a cab. Even when downtown, they don't drive around looking for fares. (Not just for Radio, this is true for all cab companies there.)
I always recommend that people visit Pittock Mansion early in their trip. It overlooks the whole city and the surroundings of the city (Columbia Gorge, Cascades, Mt. Hood). It's a free thing to do that has tremendous payoff. It allows you to get a good handle on the layout of the city in one fell swoop. Makes the rest of the trip easier. Note: I'm not talking about going IN the mansion.
Free Geek is a technology-only thrift-store. There's room for improvement but it's pretty great. I buy stuff there often. http://www.freegeek.org/
There are A LOT of tech-related meetups that go on here. Check upcoming.org for your flavor of discussions.
Mostly, I recommend just chilling out a coffee shop like Stumptown.