Just gonna throw out a few of my favorite light novels. I'll separate them according to animated and only novel formats. I'll also leave personal ratings on them based on: How it compares to the anime/manga and if I would recommend it/quality.

I will also be including links, if available, to where they can be read online. Keep in mind full credit for the translations currently only goes to Baka-Tsuki and all the amazing work they do. I also will not be posting any links to any series which has been licensed in the US. Several of these I have read several times so I will give any information or feedback I can if anyone wants.

Animated:

Sword Art Online - Better than the anime | Would highly recommend. | 10/10 (Completed translation)
Monogatari - Prefer the anime | Would recommend | 9/10 (Nowhere near finished translation)
Infinite Stratos - Prefer the LN | Would likely recommend | 7/10 (Completed translation)
Accel World - Prefer the LN | Would highly recommend | 9/10 (A third finished translation)
Baccano! - Prefer the LN | Would highly recommend | 10/10 (Mostly finished translation)
Fate/Zero - Prefer the anime | Would recommend | 8/10 (Completed translation)
Toradora! - Tied with the anime | Would highly recommend | 9/10 (Completed translation)
To Aru Majutsu no Index - Prefer the LN | Would highly recommend | 8/10 (Translation has not started)
Welcome to the N.H.K! - Prefer the LN | Would highly recommend | 10/10 (Licensed in the US)
Boogiepop - Prefer the LN | Wouldn't recommend | 6/10 (Licensed in the US)
FLCL - Prefer the anime or manga | Wouldn't recommend | 7/10 (Licensed in the US)
Shakugan no Shana - Prefer the LN | Would recommend | 7/10 (Licensed in the US)
Zero no Tsukaima - Prefer the LN | Would definitely recommend | 8/10 (65% translated)
Baka to Test - Prefer the LN | Would definitely recommend | 9/10 (Completed Translation)
Ore no Imōto ga Konna ni Kawaii Wake ga Nai - Prefer LN | Would definitely recommend | 10/10 (Completed Translation)

Light Novel Only:

Fate/Apocrypha - Would highly recommend | 9/10 (Nowhere near finished translation)
Bungaku Shoujo - Would highly recommend | 10/10 (Licensed in the US)
Zaregoto - Would highly recommend | 10/10 (Nowhere near finished translation. Volume 1 and 2 are licensed in US.)
Faust - Would recommend | 8/10 (Licensed in the US)
Psycho Busters - Would recommend | 7/10 (Licensed in the US)
.hack//G.U. - Would highly recommend | 9/10 (Licensed in the US)
Slum Online - Wouldn't recommend | 5/10 (Licensed in the US)

I'll add more later. My back hurts.

--Updated 08/07/13--

Darn it, You already got the one I would recommend (Sword art online). 

Hmm.. is there one for To Love Ru..... no I checked...

 That just means it's double recommended now!

That LN was crazy good.

It amazes me sometimes how different a light novel is compared to its counterpart manga or anime. A good example of this would be Sword Art Online but I digress. I could be wrong but I don't see any love comedy Light Novels recommended. 

 Hmm. No there isn't. Light Novel wise I started collecting them via the show that never finished. Or I wanted to know more about it. I haven't ventured that far into reading some romance comedy genres. But thanks for the idea. I'll definitely check some out and post up what I think. Thank god light novels are short.

And yes, light novels have a lot more in them. The SOA is a definite example. Others just give a more elaborate presentation. In Baccano! you actually learn about the histories and gain the significance of the train and the gang rivalries and how they truly formed. But the actual experience is pretty spot on in comparison of the anime. Characters were very well portrayed and the world was exactly what you imagine. That's the experience I look for in them.

No Ore no Imouto!? I'm offended! 

 Oh a recommendation thank you for the suggestion. We are looking for them.

By... 'TheAwsome"

 haha. I still need to update. Just give it time. Been trying to get other threads up and going.

But thanks for hitting this and reminding me. I got tons more to add.

Ore Imo is amazing in light novel. There's so much more story to tell and you get so deep into the relationships.

 To-Love-Ru light novel?

 Is there a light novel?

 I don't know I'm asking....

By... "TheAwsome"

 Give me 5 minutes. I'll hit it with a massive research bug.

 Thanks....

If it's not on Baka-tsuki, there's little chance you'll find it translated if there is one.

 You shall not destroy my hope! But yes that makes sense....

By... "TheAwsome"

Actually much less cause it's definitive.

Question the source all you want, it's likely accurate. Wiki To Love Ru

I highly doubt there is one. Anime News Network shows nothing as well as MyAnimeList.net.

If the series started as a game, or visual novel, and received a manga and anime, I highly doubt there will ever be a light novel. Normally if a series has a light novel they go to manga or anime, not to Visual Novel. Only some cases. I think Fate/Stay was one of the only exceptions. And that started as a game. I think only the newer adaptations received light novels.

So unlikely. Though with a visual novel you can get all sorts of information that you'd be craving for. They're practically filled with the same content as a light novel. Just not as much narrative, obviously.

 Yeah. Baka-Tsuki pretty much has the strong hold on it right now. Though with the arrival of Suimin Chuudoku they might one day have some competition. But as of now, there isn't much hope for it being translated.

If you want raw, there still isn't hope cause I don't think it exists.

 Yeah I know it was a long shot. But I find the Manga more then filling enough. Thank you for the help good sir.

By... "TheAwsome'

 Absolutely. You know I got your back. I don't know too much, but I know enough to figure out most of this stuff.

Not sure if this is good but there is a light novel for "Baka to Test". I found the series very hilarious but as I think back to it there were many character development points I saw so the love came about the right way. Now I never read the Manga but from my experiences the Manga usually go deeper then the Anime and Light Novels go even deeper so I'd say it should be good hope this helps.

By... "TheAwsome"