Here is a weak-ass article that describes how cloud storage for bookmarks works for chrome and firefox separately, nothing about IE (because there probably is nothing):
http://www.pcworld.com/article/2045685/seamlessly-sync-your-data-across-devices.html
According to this, there is a way to synch stuff using Windows 8 and a "Microsoft account," none of which I want to have.
http://windows.microsoft.com/en-us/windows-8/sync-settings-pcs
This article gives the following options: Use Windows 8, manually shuffle favorites folders around with SkyDrive or another cloud options, or use Xmarks which seems promising. The cloud storage idea is presented with a kinda nice trick; apparently IE lets you define a location other than the default location for the favorites folder, so if you define it as being in a folder that is automatically synched with the cloud, then this option becomes much less manual.
http://www.howtogeek.com/131249/how-to-synchronize-your-internet-explorer-favorites/?showcomments=1#comments
Here is another example of doing the cloud storage option by redefining the location of the favorites folder:
http://desktopdeploy.wordpress.com/2013/03/02/sync-internet-explorer-favorites-with-skydrive/
Here's an article about how agonizingly hard it is to synchronize bookmarks between Firefox and IE:
http://www.pclicious.com/sync-your-bookmarks-synchronize-bookmarks-between-ie-internet-explorer-and-mozilla-firefox/
Some cloud bookmarking services exist as something called "social bookmarking" which is intended on being like tumblr or pinterest or something but just with links. This is clearly not what I want, but there might be one of these that offers sufficient privacy for my purposes. The main thing is that none of these are really oriented towards downloading the links back into Favorites or local bookmarks.
http://en.wikipedia.org/wiki/Social_bookmarking
One of these Social Bookmarking services, Delicious, is sufficiently hated that there are several articles about alternatives to it:
http://thenextweb.com/socialmedia/2011/03/16/8-better-ways-than-delicious-to-bookmark-content/
Here's another article about online synch services. Xmarks comes up several times, but one commenter points out that Xmarks reserves the right to publish and otherwise mine the information. Another commenter mentions something called BookmarkSync and has a link to a different Wikipedia article comparing online sync tools.
http://softwarerecs.stackexchange.com/questions/3317/bookmark-sync-tool-between-internet-explorer-firefox-chrome-safari-and-opera
The Wikipedia article in question:
https://en.wikipedia.org/wiki/Comparison_of_browser_synchronizers
Here's an unsorted pile of ways to synch bookmarks, from IE to Chrome, from Firefox to IE, and some online services:
http://mashable.com/2007/09/20/sync-bookmarks/