The only one that really gets to me:
If you're interested in the issues themselves, QuirksMode.org is an amazing resource I used every day before making the leap to client-side libraries. Also check out John Resig's The DOM is a Mess presentation at yahoo, which gives a lot of theory about how to deal with cross-browser topics efficiently.
However, if you're interested in simply having them solved, your question is an excellent example of why many consider using client-side libraries like jQuery, YahooUI, MooTools, Dojo, etc. With a thriving community, talented people and corporate backing projects like those allow you to focus on your app rather than these issues.
Here are some jQuery examples that avoid much of the cross-browser frustration and can really make all of this.. fun.
Cross-browser mouse click binding
$('#select anything + you[want=using] ~ css:selectors').click(
function(){
alert('hi');
}
);
Cross-browser HTML Injection
$('#anElementWithThisId').html('<span>anything you want</span>');
Cross-browser Ajax (all request objects are still made available to you)
$('p.message').load('/folder/file.html');
And what really blows me away, load a data subset with selectors (see manual for details)
$('p.message').load('/folder/file.html body p:first-child');
Now, how all this really starts to get fun: chaining methods together
$('ul.menu a').click( // bind click event to all matched objects
function(evt){ // stnd event object is the first parameter
evt.preventDefault(); // method is cross-browser thx to jquery
$(this) // this = the clicked 'a' tag, like raw js
.addClass('selected') // add a 'selected' css class to it
.closest('ul.menu') // climb the dom tree back up to the ul
.find('a.selected') // find any existing selected dom children
.not(this) // filter out this element from matches
.removeClass('selected'); // remove 'selected' css class
}
)
Reminds me of Joel's Can Your Programming Language Do This? article.
Taking all this to a theoretical level, true advancement doesn't come from what you can do with conscious thought and effort, but rather what you can do automatically (without thought or effort). Joel has a segment on this in Smart And Gets Things Done regarding interviewing questions and smart developers, completely changed my approach to programming.
Similar to a pianist who can just 'play' the music because she knows all the keys, your advancement comes not from doing more things that require thought but rather more things that require no thought. The goal then becomes making all the basics easy.. natural.. subconscious.. so we can all geek out on our higher level goals.
Client side libraries, in a way, help us do just that. ;)