Include personal link to poster in Graduate School CV
In general, anything that can help folks access your works easier from your CV is a good thing.  I include links in mine for any articles that are in open-access journals or conference papers that are in public archives.  For the poster, though, make sure it's well proofread and up to date research, I think - I wouldn't go back and put all your posters online, maybe just your most recent ones?