Another possibility (if you have the stomach for it and if your local economy supports it) is to become an independent consultant. Most of the contracts I see are hourly; work more than 40 hours, and you bill more than 40 hours. One downside is that you have to plan for downtime, though most of the decent consultants I know have minimal downtime. Another downside is that you are responsible for your own taxes and benefits; for many people, that's more than they want to deal with. It's not for everyone, obviously. But if you can handle the extra accounting (which, on the whole, isn't that much) and the increased uncertainty (which may not be that much more, depending on your local market), independent consulting can provide you with a decent income *and* the ability to charge by the hour.

I'm a fairly serious amateur photographer, and I used The GIMP almost religiously (on Linux) for a number of years. But I finally outgrew it and switched to Photoshop (and bought a Mac on which to run it, 'cause I simply can't abide Windows). Here are some of the reasons:

Adjustment layers. The GIMP needs adjustment layers just to be taken seriously, in my opinion. I cannot overstate the power, convenience, and usefulness of adjustment layers.

16-bit color support. 8-bit just doesn't cut it.

Alternate color spaces. (And not just CYMK.) This is an absolute must if you're at all serious about printing photos.

Better B&W support. Photoshop's support for grayscale is outstanding. It has features The GIMP simply does not have, such as a more intuitive channel mixer; the Calculations feature; a new CS3 B&W adjustment layer (which effing rocks); a photo filter adjustment layer (useful for toning the final B&W); support for duotone, tritone and quadtone (albeit only in 8-bit mode), with a full suite of built-in Pantone filters.

Better RAW support. Photoshop's Camera RAW capability just gets better and better. Before I switched to Photoshop, I purchased the BibblePro tool (which runs on Linux, Mac OS X and Windows) because of its outstanding RAW support. At that point, I still planned to stick with The GIMP, but I actually paid for a commercial tool because The GIMP's RAW support just doesn't cut it. (I still use Bibble.)

Photoshop's healing brush, CS3's quick selection tool, and a host of other tools make selections and other common manipulation tasks easier than they are in The GIMP.

Photoshop's history palette. If you've used it, you know what I mean.

Recordable actions. They work like macro recording in your favorite text editor: Turn it on, and it records what you do until you turn it off. And you can save the macros. I created a Contrast Mask macro in 10 seconds; it's now available to me whenever I need it, at the press of a button. I'm a professional programmer, so writing a GIMP plug-in isn't especially scary for me. But it still would've taken me longer to create the same kind of plug-in for The GIMP, and it would've been a lot more annoying to do. (Yeah, I know The GIMP already has a Contrast Mask plug-in. That's not my point.)

Workflow support. Photoshop works well with Bridge, which eases the workflow when you have 200 images from a shoot that you have to sift through, before deciding which one(s) to spend serious time working.

Commonality of terminology. I participate on some photo enthusiast web sites, and I frequently read tutorials on image manipulation. They are, almost without exception, Photoshop-oriented. I got tired of trying to translate Photoshop into GIMP. Even if The GIMP doesn't support all the features Photoshop does (and, frankly, I don't see how it'll catch up any time soon), the features it does support should be supported as closely as possible the way Photoshop does them. These tools are so complicated that even the pros refer to tutorials. If those tutorials and tricks could be more readily applied to The GIMP, without the necessary head-scratching translations that are often necessary, it sure would help.

HDR. I don't do HDR very often, but when I need to do it, I sure can't do it with The GIMP.

Stitching. Photoshop's stitching plug-ins are surprisingly good. Again, as with HDR, it's not a feature I use every day, but when I need it, nothing else will do.

I'm sure I could come up with others, but those are the ones that leap immediately to mind.

I like The GIMP; it's installed on every desktop I use. It's also installed on my Mac laptop. It's damned useful for plenty of image-related tasks. But it doesn't hold a candle to Photoshop, and until it supports at least a large subset of the above capabilities, it hasn't a prayer of being taken seriously by most photographers.