Question: Sometimes I download an app but it fails to download or install. The message just says that, no further details. It generally seems that the app never installs after that. Is there anyway I can find out more details about why it failed? Is there any good way to get stuff to install after this has happened.

I am using Android 1.5 on a T-Mobile Pulse/Huawei U8220

Answer: 
Can you get any app to install? First thing to always try is to reboot the phone. 

If that doesnt work, try downloading aLogCat from the market (if you can install it). If it installs, then go to the market and try to download the app you're having issues with. If it STILL wont download, then open aLogCat and look at the system log entries. Then you should be able to glean a little bit of info of why its not installing. I know this is not a 100% answer of what you're looking for, but it does help and has helped me before.
Are you out of internal storage for apps? Have you tried a hard reset? Can you upgrade your phone to a newer Android release? Personally I would try upgrading your device first then see if you still have problems.