I'm a grad student. Recently, a woman who shares the same sup as me, asked if she could take a look at the work I have done. I agreed and as soon as she did, she pointed out some minor typos and remarked that if I wanted then I could send her my work for her to review. Now, this woman is very go-getting but hasn't really been attending to her thesis so I'm wondering whether she in fact would like to use me as a means to help her conduct an early lit review for her very similar thesis topic. I'm not sure what the best course of action to take is. Is sharing caring? Can something positive be gained for both of us, or is this a bit of an odd exchange whereby I will have my worked nit-picked for typos whilst she reaps the content related benefits?

Any ideas?

sounds fishy to me, as you say - what do you have to gain? You have a supervisor already. She is not qualified to make any useful comments on your writing anyhow.

No, if you're going to give your work to anyone to proof read besides your supervisor, then give it to a post doc you feel you can trust, or someone much further ahead of you, not someone behind. Sounds dodgy to me!

My sup asked me to send my proposal to her to act as a template, so I felt obliged to as he really helped me with it. Did I really have a say in this?

I'd be tempted to send the bare minimum i.e. headings of sections. And then if asked for more, send without the reference list and any insightful writing taken out.

I'm afraid I had to send her the full proposal. I felt in an awkward situation over that. Is it worth talking to my sup about this or will I come off as someone who is selfish... I mean he is trying to build up an army of students for himself too! Is it bad to feel protective over my research at masters level?

If I was you I'd let your supervisor know asap of the situtation, just in case she tries to pull it off her as her own work. I wouldn't share work with other students at the same level.

Agree with all on here. 

Tell sup and then give bare minimum - or nothing at all.

There is nothing worse than free loaders.  Make me so angry.   :-s

That said... its fantastic for you that she wants to copy  - you must be doing something right. Well done :-) 

Look after yourself.  Chuff