I am developing a web site with an idea that it would be a networking platform for small companies. I have registered the name (Let's call it
www.merchandiize.com for now...), however I have discovered that there was and other website
www.merchandise.com on their website it was mentioned that "patent pending" and it is a car rental website.
Would I be able to use this name after they got their patent? The business models are totally different, just
iize are different.
There is probably a patent on the actual software being used that is pending, rather than most other things. Overall, you should be fine. Trademark law would be the closest thing that would apply to you, and it doesn't apply in this case (if you're in the US at least). The reason being is that you are offering a different type of service/good than they are. There isn't likely to be confusion between merchandise.com renting cars and merchandize.com bringing networking abilities to small businesses.
As always, your mileage may vary, and don't take legal advise from the internet. If you believe that you may be crossing a line, consult an attorney for additional guidance.