I dunno if this fits your request, as it doesn't interact with snap. I put together a little app that works great for my my needs. I have multiple apps that look/work better at abnormal sizes and this allows me to build my "workspace" and incorporate them in. You highlight the window you want to resize and hit CTRL+ALT+(numbers on number pad). sourceforge /projects/workspaceutilities/ (sry I can't post links)