For instance, maybe I'm looking for a PostgresSQL tutorial. I start typing "postgres" and one of the bookmarks I forgot about from several months back appears. This approach has ended up saving me a lot of time over the years. Another cool thing is when a bookmark pops up when I'm searching that brings back memories. If the site is still up, I get a free trip down memory lane :)
My collection is at least 9 years old now. I've been maintaining the same Firefox database over the years by migrating it manually from version to version. Now it's seamless thanks to Firefox Sync. I get my bookmarks on my PC, laptop, and my phone. I have an Xmarks account as a backup, and for cases when I prefer to use Chrome.