[BirdOPrey5]

I use Chrome as my default browser and it most certainly works for me... Are you using the latest version? 5?

To have the user pick a color replace the color you want to be user selectable in your code with {option} for example:

<span style="background: #FFF; color: {option}; text-shadow: 0 0 24px #C00, 0 0 4px #C00, 1px 1px 2px #333;">{param}</span>

They would then enter the # sign and color code in the option part of the bbcode [glow="color"]glow text here[/glow].
Personally I've never seen 3 digit hex color codes before but if you say they work I believe you, you'd use [glow="#FFF"] in your example... if you want to replace both the background and color with the same color you can use option twice, but I can't see how this would work:

<span style="background: {option} color: {option}; text-shadow: 0 0 24px #C00, 0 0 4px #C00, 1px 1px 2px #333;">{param}</span>

Or it may be the last color you want to change, I don't know I can't follow your logic... but if so use:

<span style="background: #FFF; color: #FFF; text-shadow: 0 0 24px #C00, 0 0 4px #C00, 1px 1px 2px {option};">{param}</span>

Unfortunately you can only use 1 option per bbcode, though you can use the same option in more than 1 place.