I've got a few tricks for image sizing!
(bear in mind, I'm using WindowsXP)
1) right click, "send to...mail recipient" - then select a smaller size when it offers to resize (640x480) 90% of the time that does the trick.
2) failing the image resize, Photoshop: open and re-save with higher compression. I try JPG first (it's usually pretty good) and then adaptive GIF if JPG fails. Actually, I've never had to resort to GIF as long as I can remember. Even JPG at "LOW" quality looks pretty good.
BIG ISSUE: cropping! Get it tight or you'll lose detail.
Good source images help a lot. Focus, saturation, exposure and framing. Cropping's easy later but if the data isn't there, it'll never look wonderful.
Here's a few samples!
