Or "show ideas that you haven't read yet". Whether you've voted on them or not. Ideas could be flagged as "read" either automatically via scrolling or manually by the user. Kind of like an RSS feed reader. This way we don't have to hunt through hundreds of ideas we've already read to find ones that we haven't. Right now you either go to "latest" or "most popular", and the result is that all the ideas in the middle tend to get ignored unless you're prepared to spend a LOT of time going through every page.
Good idea - anything that helps more people to view more ideas (as opposed to ideas they have already seen, or ideas that have been approved or rejected) is what we need.
I suggest not presenting ideas in numerical order but randomly to each user coupled with not showing the same idea twice (in the list regardless of whether the user chooses to vote or click on it)
Selecting 'Most Popular' and other lists would, of course, show you ideas regardless of whether you had seen them before.
The 'latest ideas' button should be got rid of completely.
There is nothing inherently better or more worthy of my attention about an idea that was posted 5 minutes ago as opposed to one that was posted 5 days ago which I haven't seen yet.
And finally (but I may post this as in idea myself) ...
once an idea has been shown in the lists of a set number of people (1000? 10,000? ) then it is retired. After all it has had enough chance to get votes +/-, showing it endlessly to more people cannot be statistically significant.
This isn't really a duplicate of the "Ideas you haven't rated" idea.
As a geek with only two stars on my geek membership card, there are many ideas that I'm not qualified to comment on. Also there are many other ideas where I have no opinion one way or the other. Consequently I'll want to filter those ideas out without hitting one of the ratings buttons. I would then want to mark them as read.
However if I did want to rate an idea this would mark it as read as well.