::Wendy:: suggested enabling a means of displaying pictures on the blog without messing up the display of the whole post.
Actually, I've simply given up on the pretty diagrams since everybody seems to hate them. You may have noticed that I've been using ASCII art instead. It's certainly easier for me to write, though it's also a bit uglier.
One thing readers may not have noticed is that I try to make the article readable even without any diagrams or pictures at all. Sure, you can look at the diagrams if you want, but the article should still make sense if you don't. (And if the image is essential, I'll at least give it some ALT text.) I do this out of consideration for my readers with visual impairments.
When you're giving a talk, you have to make sure people can follow what you're saying even if they can't see your slides. They may be visually impaired. They may be stuck behind a pillar. They may be sitting so far back that they can't see your slides clearly. If your talk is being recorded, the person listening to your talk might have downloaded only the audio portion. Or your diagram may simply be unreadable.
Don't just say, "You can see the trend from this graph." Describe the trend. "The system remains responsive until traffic reaches X requests per second, at which point the throughput nosedives very sharply."
Don't just say, "This is the block diagram for our system." Describe the block diagram. "The XYZ component is the kernel-mode component upon which the user-mode components ABC and DEF are built."
If you want to point out elements in your diagram in your talk, don't just point and say, "It goes from here to here." Describe where "here" is: "It goes from here, ABC at the top of the triangle, to here, DEF at the bottom left corner." That way, people who are too far away to see where you're pointing (but who have a hard copy of the slides in front of them) can still follow along.
Basically, when you have a diagram, pretend you don't. Write your text (or give your talk) as if there were no diagram at all.