I'm trying to figure out what is the typical wage an experienced indie game programmer can expect. Note that I'm not talking here about working for an established company, but on a small independant team that has yet to establish revenue. Like a start-up that is still looking for a VC.

The incoming of a indie-developer (not an independent studio), is really low compared to wages paid in the game industry, it was $20000 per year on average (there will be a large variability). Here are the salary of different positions in the game industry 2013, and here is the indie-report.

What would be fair for an experienced indie game developer to charge them hourly (where experienced = released a couple other indie games)?

It is really hard to tell, because a startup with no to low budget will not have much to pay, but could be still quite successfully later on. Best to choose a payment yourself (what seems to be a fair compensation for your work), regardless of how much budget the indie-dev has. It would be their choise to hire you or not.

If you want to help, think about royalities kind of 'pay me x$ upfront, and once your sales surpass y$, I get an addional z$' (=> contract+lawyer !)

1. I'm trying to figure out what is the typical wage an experienced indie game programmer can expect.
2. Note that I'm not talking here about working for an established company, but on a small independant team that has yet to establish revenue. Like a start-up that is still looking for a VC. What would be fair for an experienced indie game developer to charge them hourly (where experienced = released a couple other indie games)?

1. "Wage" is probably the wrong word. "Wage" refers to hourly pay, in which the worker punches a timeclock. "Salary" is a lump sum paid per pay period. Independent contractors sometimes get paid a flat fee, or on a per-milestone basis.
2. Decide beforehand what's the minimum you'll accept. In the process, decide what you would like to get ideally. Then negotiate between those two figures. If the indie team can't pay you your minimum, wish them luck and move on.

[Edit] I'm moving this to Game Industry Job Advice, since I think the OP is asking how much he should charge (not how much he should expect to pay someone to work for him).

You can offer $15 an hour and see what resumes arrive, or offer $80 and see what other resumes will now arrive ;)

I think you can expect something in the middle say 40$ and then its up to you (amount of experience) and the circumstances of the project (type,budget) to get you to the real amount.

I think most work at this scale tends to be contract-based, payed per-project or milestone, but it depends on the structure and size of the company.

Mojang is indie, although large with lots of money, and they have proper employees. 2-3 guys working out of an apartment bedroom, almost certainly haven't got any real money to throw around (the kind of place that, if you went to work for them, you'd have to bring your own soda and hotpockets). Indie studios range the entire gamut inbetween, but most of them are probably nearer to the latter than the former if they don't have a publisher or even a VC.

Just to throw some numbers out there, after college I worked my first software job for the probationary (6mo) rate of something like $24/hr, they were a small (~20 people) company that customized software for other businesses and sold seat-licenses to said software, it wasn't gaming related. After that job, I had an offer from a fairly well-established developer who's business was essentially to crete games for big-name 3rd-party IP that was handed down from the publisher -- I think the salary they offered was equivalent to $37/hr, and they didn't offer much else in way of compensation (no signing bonus, stock, etc), except for what was a relatively good health insurance package. I ended up not accepting that position to take a non-gaming position that offered better pay and work-life balance.