It's not too dark on my monitor - cool gallery, BTW!

Maybe this might help - monitors are back-lit which means they have an inherent brightness to them.

Slap a "bright white" piece of paper down on your countertop/desk/sofa - that's as bright as it will get, and it only gets darker.

What you may end up needing to do is something like a mild "Highlights/Shadows" adjustment in Photoshop - something to bring your gain/midtones up.

Send me an image that you were particularly disappointed by the print and I'll work it over a bit and send it back to you, and have it printed again. It may just need some pre-press adjustments (yes, this is what I do for a living, and NO - I'm not even thinking of charging you).

-Lew