My URL shortening service at http://mhurl.com, that I mainly use with my blog to create Short URLs for new posts to be tweeted about, now has a preview option you can enable that will show the destination URL, which you can then decide if you wish to click on or not rather than automatically being redirected to the destination. In order for this to work your browser must be set to accept cookies. If you are like me and have 3rd-party cookies disabled, that is fine.
Once you have it set, you can test it with this Short URL which should be created after I publish the post: http://mhurl.com/2.
Even though I will not send anyone to a questionable site, I understand many would want this ability. 🙂