I've been playing guitar for about 4 years now and violin for 6 and can sight-read well on violin. I've got all the positions, scales down, etc.

Now, when it comes to technical skills, I'm much better at guitar because I practice it extensively unlike my violin which never leaves its case when not at school.

I can sight-read well on violin, but how can I apply these skills to guitar? Basically, how can I sight-read better on guitar? Any tips, sources of help, etc?
I don't play violin, but I play keyboard and guitar, and thus - relying on my experience - I'd suggest that you stop trying to apply what you learned for the violin, because it's not gonna work on the guitar. You know: the violin is tuned in 5ths, while the guitar in 4ths, and this means that it requires a totally different mental approach. So if I were you, I would start learning sight-reading from scratch.... sorry, I know that's hard now, but that's the way it works.
The only way to get better at sight-reading is to sight read. Simple, no?

This means you need sheet music. I'm sure the music teacher(s) at your school would be willing to give you copies of any songs that they have for you to play. You could also buy the sheet music (may get expensive) or (illegally) download it.

The only tip I can really give is to sight read all the time. When you're sitting at home in your basement playing alone it doesn't really matter if you're sight reading the Bb Clarinet part on your guitar because you'll be playing alone so it will sound fine.

In all honesty, I'm no a very good sight reader. I can read music in treble, bass and percussion clefs but I'm quite inept. I really do need more practice too.
I asked about this just about a week or two ago. Knowing that you've got a really low E, a low A, D, G, B, and an E at the top of the treble clef, work from there. I stumbled across a link to this site: http://www.creativeguitar.org/ in the Acoustic & Classical Guitar Forum. It has around 3000 pieces of sheet music. Since I need a good volume of material to practice on, I find it helpful. All I can really say is to practice.
RIP Terry Kath (1978)
I'm just starting to learn sight reading now, I started on Autumn Leaves, a jazz standard, so once i've learnt it it'll actually as well as a tool for sight reading...
Quote by cakemonster91

*chuckle* A peanut. With a face.

Go to your staff paper and re-write this song a half step down so on the paper it'll be like you have a "C" just move it down to a "B#"

Know your theory, then play like you don't.

What's the website where it quizzes you on key signatures and notes and the such? I can't find it.
Well, I play violin and the only thing that is helped me with was knowing how to read music before starting guitar because the tuning on a violin is different therefore the notes are in different places.

You should buy a book with simple pieces and just sight read through them, there are loads around. It's not that hard really. Reading music has been mystified, all it takes is a bit of practice and dedication and you have a pretty good headstart.