If you're smart, you probably already assumed the correct answer is, "it depends". And I assume that you're probably looking for something a bit more specific than that. Residential and commercial project are significantly different - I'm guessing that you want to know what an architect charges for residential projects.
A better question might be, "how does an architect charge?" And for residential projects (especially new construction), the answer is almost always a percentage of total construction costs. There is a range here, but I would anticipate at least 5%, but more likely a figure that approaches 10% of the overall construction budget. For difficult projects that tend to include many difficult to manage variables (like an extensive renovation of an existing structure), some architects favor an approach where they simply bill hourly for their time. This is mitigate their risk, not yours. In this scenario you solely bear the burden of additional costs incurred by unforeseen circumstances. Hourly rates will tend to vary widely depending on numerous factors (experience, current workload, level of interesting in your particular project, etc.).
Keep in mind that architects often tend to view themselves more as artists while the people who procure their services often tend to see them more as just that – people providing a service. At the risk of espousing a broad generalization, architects tend to be a hubris-filled crowd. They tend to think that they are providing you with a service that no one else can. Don't buy it. Shop around and become acquainted with your options. Most architects publish quite a bit of information about their previous work on the Internet. Use that to your advantage and do some homework to find architects in your area who have done work similar to the project you have in mind and - perhaps more importantly - have demonstrated an ability to express the design aesthetic you are hoping to achieve by procuring their services. Once you've done some research, set up meetings with 3 architects to meet them in person and to discuss your project. Come prepared to articulate a vision of what you want to accomplish. Your instincts will serve you well and you'll be able to tell who you'd most like to work with.
Another factor to consider is the exact nature of the services you are getting from the architect. There are a number of services that architects and their firms provide - and they're not all the same - so make sure you understand clearly what the architect is proposing to do (and what they're not going to do) when you attempt to compare bids. Otherwise you might end up comparing apples and oranges.
One final thing to consider if you are indeed contemplating a residential project - the majority of permitting jurisdictions (the city or county who will approve your project by granting a building permit) in the U.S. don't require that a residential construction project be designed by a licensed architect. Another (often less-expensive) option is to hire a designer/draftsman to draw up construction documents suitable for obtaining a building permit. This can be a good option for someone who already knows something about design and construction, has a relatively clear vision of what they'd like to achieve and wants more control over the project. Designers will still likely have to collaborate with a structural engineer to provide structural drawings (the documents that more specifically tell contractors how the building is to be put together) and their corresponding calculations, but architects farm this work out, too.