What I learned is that there are a few different types of sites. There are the free sites which can be unsafe to download from. There's the pay-per-use sites and now that iTunes is carrying apps, this is a viable option. Then there are the unlimited downloads sites that charge a one time fee for access to software, games, movies, TV shows, music, and more.
The unlimited download membership sites are interesting, especially if you like to download all of files. After you join, you will have access to all of the downloads. Plus, many of these sites also offer tutorials and helper software to transfer the files from your computer to your iPhone. This alone can come in handy as it can be a little tricky if you've never done it before.
Pay-per-download sites like iTunes are also popular way to get iPhone software downloads, music, movies and other goodies. The only drawback to this is that it can get costly as few few bucks here and there add up over time. The downloads themselves are not expensive, but the lack of willpower to stop can be. Like the unlimited download sites, the pay per download sites are a safe option.
Free download sites are the ones you have to watch out for. Many of them are of questionable legality at best and they have a reputation for being a breeding ground for viruses and other malware. Free is not always such a good deal if it causes damage to your system or files. Its a safer choice to avoid these sites altogether.
As iPhones evolve and become more widespread in use, it will be interesting to see what types of software and distribution systems are created to fill the demand for iPhone software downloads. For now, we have a couple of good options to get our iPhone download fix.