One of this things seams to be round corners. Often the developer ends up using images of round corners or other weird methods.
What only a few people seam to know is that you can get round corners very easy with CSS.
Check this out (each is for a different Browser Toolkit, just include all of them every time you want rounded corners):
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
-khtml-border-radius: 5px;
(Including the "-")
this should look like this:
This box should have round corners
For IE users, fear not! There is a project that does the job too. More info here:
http://code.google.com/p/curvycorners/
Stay tuned, post about Web Fonts coming soon with another great discovery to finally making the Web beautiful.