Can I use a flatscreen monitor in place of my tv for the usual cable providers like Comcast, DirecTV, Optimum, etc? I'm not asking about non-cable stuff like Hulu or Netflix that I can "just watch on my computer," I'm talking about traditional cable tv.

You;ll need sound. But I don't see why not...

Something extraordinarily obvious...which I hadn't thought of. Thanks Pali!

I don't know how your cable providers do things over there. Provided that the actual signal is processed by an STB, and that the only thing actually going into your TV is an HDMI cable, I don't see why not, except that, as paladin181 says, you'll need sound, but then some monitors have that. If not, your STB needs to be able to output sound from a separate set of plugs, and of course you need to have an amplifier and some speakers to plug into it.

The monitor shouldn't matter at all as long as you can hook up your cable box to it.

An alternative solution is HTPC. Turn your PC into a Home theater PC.

There are two problems with monitors as TV, as others mentioned many don't have speakers, but that can be solved of course (some support external speakers or you can hook up a receiver in the middle). The second is that they have no Tuner in them so you need either a box provided by the cable company (with for example HDMI out) or a computer with a tuner. Otherwise there is nothing against it.

It works, you just need speakers and a set-top box. Some Samesung monitor+tv hybrids also had Conax module spots in them aswell, but they were small (can't remember that well, 27" ? or something like that, maybe they have shat up newer bigger models aswell)

Something like this:http://www.samsung.com/uk/consumer/it/monitor/tv-monitor/LT22D390EW/XU


BUt I'd rather recommend a Eizo or Dell UltraSharp model if you need quality

How the technology advances.... I still recall the times when I was wishing that I could connect my PC to my TV, and connect my Playstation to my VGA monitor (I even bought some expensive signal conversion box back then for this latter case, but it worsened the output, and wasn't very user-friendly. But at least it worked for its intended purpose.).

Nowadays you don't have to think about it much. Want to connect your PC to your TV, or your gaming console to your computer monitor? Fine, just do it. Heck, my mind was blown even how I could connect my Android phone wirelessly with Bluetooth to my external speakers I use with the TV, in order to play music with the phone.

We live in the space age of computing!

Way better than proprietary set up boxes such as apple, roku or whatever, if you ask me.
Slick desktop cases are everywhere. HTPC is a format that has evolved tremendously since the past decade.

No time to building a Home Theater pc? Steam Machine. No joke.
Don't like SteamOS? Boot the thingy with XBMC and you're set! Steam controller is surely a plus, I suppose.