I'm an avid user of Xmarks (formerly Foxmarks) as are probably many of you. I browse the Internet regularly on three different computers, and so it helps immensely to have all of my Firefox bookmarks and passwords synced. But the one fly in my ointment has been my iPhone's mobile Safari installation -- because I don't usually use Safari as my browser, I haven't yet figured out a way to get all of my usual bookmarks on to the iPhone.
Until now: this writeup by Shawn0 (via the good folks at Lifehacker) presents a quick workaround to get your Xmarks-synced bookmarks up and running on your iPhone. Unfortunately, he uses Internet Explorer to do it, but given that we're all on Macs, I discovered that it worked just fine with Safari. Set up Xmarks on your Safari installation, sync it up with your usual bookmarks, and then set iTunes to sync your mobile browser's bookmarks with Safari. The one big drawback is that you'll have to start up Safari every once in a while to make sure your changes get all the way out to the mobile device, but that's better than not having them synced up at all.
And yes, you MobileMe users are laughing at us Xmarks users right now, because Apple's service syncs all of these things automatically. But I've never known Xmarks to go down, and this solution costs the low, low price of free per year. If, like me, you haven't landed on a solid way to sync bookmarks out to the mobile browser yet, here you go.