This happens on my Droid with Verizon as well.
3G coverage seems to fluctuate wildly just sitting at my desk or at home.
I can try to download email and it will timeout, but while surfing the web, different websites will load immediately or sometimes not at all.
When I'm at home at least I can hop on the wifi and things improve somewhat.
I'd really like to have a network quality feedback app for Android like AT&T has for the iPhone. Actually I'd like to have a feedback app for a lot of the things on Android, including the Google Maps driving directions BETA won't be replacing my TomTom anytime soon.
I sign up for BETA programs, I've been a real QA tester, I don't mind using BETA software, but give me the ability to provide feedback right there when I'm using the phone.