Is there a resource for pasting student citations to check format accuracy?
The library has Citing & Writing research guides that provide examples of citations, which you can check your citation against. The APA guide can be found at: http://library.uhd.edu/apa?hs=a and the MLA guide can be found at http://library.uhd.edu/mla?hs=a.
If you are looking for a citation builder/generator, there are many available on the Web. You should be aware, however, that these tools are not always reliable. If you do choose to use a citation builder/generator, I might recommend that you use NCSU library's citation builder available at http://www.lib.ncsu.edu/citationbuilder/ or EasyBib at http://www.easybib.com/ (MLA only, other styles by subscription).