One is Web sites that gratuitously make ad banners load synchronously rather than asynchronously; otherwise you could just scroll down and read the content. Then the ad servers have an incentive to not be slow -- if they are, the ad is scrolled out of view before it's more than a blank rectangle on the screen, and never gets viewed! Instead, they presumably strong-arm site operators to use evil Javashit to make the page load pause until the banner is done loading or has aborted, and they then have no incentive to make their servers fast.

A bunch of related evil tactics, all using Javashit:
* Disguising link destinations (Firefox has a
  setting to stop this)
* Messing with the right click menu functionality
  (ditto)
* Making shift-click selection not work (Firefox
  doesn't help here)
* Popups (Firefox is a partial help; popups
  triggered by something other than page load
  aren't stopped, and neither are those fake
  popups that use flash or JS to draw directly to
  the framebuffer, and which have a nasty habit of
  making a page unreadable and unusable.
  Photobucket provides an example: get an account
  and upload an image. When you double click an
  item in the file chooser, there's a roughly 33%
  chance a new browser window opens and
  immediately goes to some full-screen ad page.
  Unfortunately I don't see how to avoid layer
  based popups and popups triggered by form
  filling/other user action without blocking
  desirable events, such as web forum links that
  open the link in a new window so you don't lose
  your place in the forum.)
Of course, sites that abuse Javashit also tend to replace ordinary "a href=foo.html" links with "a href=# onClick=blahblah" gratuitously to punish people who disable Javashit; the site becomes unnavigable, even though there's nothing about the site that means it couldn't be made navigable with JS disabled. Even worse, some refuse to render any content at all if you turn off JS, just giving some bullshit about how JS is required. I know enough about computers and the Web to know that to display some text, some inline images (including ad banners), and some functioning links does not require JS in any way shape or form; they want to make you use it so they can spam you, pop up at you, slip you some spyware, try to extract your email address to spam, and so on. Firefox will protect you from most of these abuses, but it doesn't stop layer-based popups, popups triggered by filling in a form field (e.g. Photobucket's image upload form), or scripts that interfere with selecting and copying text off a page (have these arseholes not heard of "fair use", not to mention "resistance is futile, retard" and "It's my web browser and it's my computer!"? I will have my excerpt if I want it, over your javashit's dead body if necessary, also known as the stuff displayed by "View ... Page Source", so there's really NO FRIGGING POINT, it just ANNOYS ME!!! GRR!!!)

On the other hand, my experience blocking ads via hosts file is less than stellar. There are two problems:
* When page loading is deliberately and
  gratuitously modified to pause until an ad
  finishes loading, the result is invariably very
  slow page loads, because it waits ages for the
  loopback connection to timeout on my stealth
  firewall.
* When page loading is yadda yadda and an ad fails
  to load entirely, in some broken Web browsers
  (*cough*IE*cough*) the whole page load aborts.
  (This is fixed by using Firefox.)
* The proliferation of zillions of redundant
  ad5838584654.357832486584.six-zillion-and-three.spammer.com
  ad servers means that to put a dent in it you'd
  need six zillion entries in your hosts file. And
  when you have six zillion entries in your hosts
  file, every name lookup takes six zillion hours,
  because Winblows is too stupid and brain-damaged
  to actually cache the fricking results of name
  lookups and uses bogo-sort somewhere in the code
  that reads the host file; meanwhile host file
  parsing and name lookup code are being
  overhauled with even more "necessary security
  checks" in Windows Vista betas while Madison
  Ave. execs pass more thick wads of C-notes to
  Bill G. under the table at the local pub after
  their weekly chummy 18 holes at Pebble Beach.

Ad blocking that stops the browser requesting the stupid crap in the first place is, IMO, the only solution; that and staying the hell away from the pre-lubed^H^H^H^H^Hinstalled MS rectum^H^H^H^H^H^Hbrowser, that is. (And their other orifices^H^H^H^H^H^H^H^Hnetwork tools too, particularly Outlook, the feature set of which Spamford and his ilk and companies like 180 solutions no doubt paid a pretty penny for...)

More generally, it's time to collectively wean ourselves off MS and all other corporate crap when it comes to software. Corporations that make software have split incentives these days and can't be trusted. More and more, the feature set of software and even of entertainment hardware (game consoles, video players, widescreen TVs) is being decided not by the wishes of customers but by big businesses with consumer-hostile agendas, from the RIAA and MPAA to advertisers and spyware vendors and the government and their cronies.

The decision we will face in the next decade is nothing less than whether the ultimate result of technological advance will be individual empowerment or the realization of Orwell's worst fears. Accelerating change and the disturbing trends in everything from DRM to MS Vista make it plain that we have at most 10 years to take back our computers, if that. At the end of that time, individuals will be empowered again in participatory democracy and economics ... or we will be permanent residents of the Matrix, existing only to serve a vast government-industrial machine that demands to be fed with ever more docile consumers whose only choice will be to buy from the "company store" and work for the company (there will, for all intents and purposes, be only the one) or to starve (or be labeled a "terrorist" and shot on sight by the FBI, the metro police, or some other law enforcement agency the corporation has purchased). Our current ability to walk out in the woods without being metered by the footstep, read books without paying by the page, pirate music without too much risk of a lawsuit, speak our minds and be heard, tape shows and fast-forward the commercials, block internet ads, uninstall things on our own computers, and so on will all disappear. If we make the wrong choice in the next ten years, then by 2040 there won't be an unowned place or person on the planet. A romance novel will cost you a dollar a page, and you'll have to pay every time you reread it. You won't be able to visit Yosemite Park; you will be able to pay an arm and a leg a day to look around a cheerily-redecorated, rubber-surfaced subset of something that vaguely resembles it but is named Disneywood Park West instead. Trying to borrow someone else's CD will get you ten to fifteen; actually burning a mix will get you the chair, on trumped-up terrorism charges as a grave threat to national security who tried to undermine the economy. Question official doctrine on 9/11 and your question mysteriously disappears; anywhere copies of it got, something deletes it, and everyone denies ever having read it. To do otherwise risks imprisonment, or at least being muted -- all your speech, writings, etc. made to disappear, past and future, thanks to Fritz chips mandated in all technology.