TeXlipse is an Eclipse Plugin that allows you to have control of your Tex files, compile them, and convert them to PDF. It runs through Eclipse and its very easy to use. Using Eclipse as a tool for Tex is nice because you can use all the other Eclipse’s tools to be more productive(CVS, SVN, Mylin etc).
The only requirement to install Texlipse, is to have a Tex toolchain already installed on your Mac. The recommended way to have the whole toolchain, is to install MacTex. In order to install it, just visit http://www.tug.org/mactex/ and install it(the file you are about to download is about 1.2 GBs!).
After you have installed MacTex, you have to install TeXlipse.