Right now I have 100 tabs open, many of which are HN posts or links from HN posts that I still want to check back on. That's down from the low 200's a week ago. Once a week, before I read more HN, I go through my tabs and either read it and close it, save it for next time, or say "realistically I will not get to this within the next year due to (other projects I want more)." and close the tab.