I tell everyone they should have Firebug or its equivalent installed, and know how to use it. I believe that people will find it invaluable if they're designing a page and want to test something. They might want to do some in-page scripting. They can examine the source for ideas, or to discover hidden items. But most importantly, they can use it to fix your stupid, unreadable, over-styled web page.
The development of HTML5 means that browsers have gotten more powerful, more elaborate, and more interactive. It also means that they can be annoying in new and subtle ways. Back in the day, page authors used <blink> and <marquee> to create eye-catching elements on their flat gray canvas. Nowadays, thanks to pre-made CMS templates, the web superficially looks better, but it's not necessarily easier to read. Take three examples:
Even worse are the people who have realized you can give the shadow an offset of zero pixels. If the shadow is dark, this ends up looking like the page got wet and all the ink has run. If it's a lighter shadow, you've got a poor man's text glow. Remember how classy text glow was when you used it on everything in Photoshop? Nobody else does either.
I'm not an expert in typesetting or anything, but the effect of these changes--besides sometimes giving Comic Sans a run for its ugly font money--is to throw me out of my browsing groove, and force me to re-acquire a grip on the text with every link to a custom page. If I'm not expecting it, and the font is almost the same as a system font, it looks like a display error. Either way, it's jarring, and it breaks the feeling that the Internet is a common space. Eventually, we'll all get used to it, but for now I hate your custom fonts.
It's no wonder, in an environment like this, that style-stripping bookmarklets like Readability caused such a sensation. There's a fine line between interactive design and overdesign, and designers are crossing it as fast as they can. All I ask, people, is that you think before getting clever with your CSS and your scripts. Ask yourself: "if someone else simulated this effect using, say, a static image, would I still think it looked good? Or would I ask them what Geocities neighborhood they're from?" Take a deep breath. And then put down the stylesheet, and let us read in peace.