The income of people making more than around 200k a year, capital gains, and B&O.

I almost hate to bring it up, but the whole aspect of internet sales of goods circumvents collection of sales taxes that support local infrastructure and public services. I do purchase things over the internet but I do not do what many people do, which is go to local stores and physically look at goods and then run home and order it online. Some online businesses collect sales taxes and of course if the source of the online business is located in this state you will pay it (example: Amazon).

Many would bring up the aspect of sales taxes as being a regressive means of collecting funds as all people have to shop for goods regardless of their level of income. I wonder however how much local businesses would benefit if just the aspect of having an even tax structure on sales existed (no matter what the source - local or shipped from out of state). How many billions of dollars a year of sales in this country are spent this way. I dare say that our current sales tax levels would not be as high as they are now if that revenue stream had not been avoided by shopping long distance through our computers.

Rich people. I don't smoke anymore so I'll be an asshole and say cigarettes as well. Prices should start at $10/pack.
Sugar. Including corn syrup. but not maple syrup. Tax the shitout of candy and soda. I know we tried. Try again.

First, we really need to work on educating people on the absolute dysfunction caused by Tim Eyman's 2/3rds majority nonsense. People, POOR people, voted for that. Why!?

Did the legislature grow a spine and approve the yacht/aircraft luxury taxes? I know there was some gesturing in that direction. Not sure if it was serious.

Speaking of that, car tabs should be progressive. A Hummer limo should get the maximum amount.

Gas, in respect to its increasing scarcity, but that's not a WA-only problem.

Car tabs are artificially low, with the benefits skewed towards wealthy car owners and public transit taking it in the shorts. Anyone remember I-695?

And what Protosaurus said x 1,000.

Nevada
or
Texas

Yes, financial assets.

That's why you should support HB-2100, a tax on assets above $1 million.

I like just about every other suggestion here so far.

I would add that I probably consume more cans of soda than anybody you know--I literally fill my trunk with half-cases when they put it on sale over holiday weekends. I totally supported the soft drink tax because I know the stuff is an optional luxury, for me and for anybody. Any food or beverage you consume because you like it but don't really need it--it has negligible nutritional value, like sodas, candy, chips, etc.--I'm fine with paying a tax on those. Can't believe we let the soft drink industry turn that into an issue personal freedom and government oppression.