With sites that connect with limited amount of bandwidth here are a few things I've used.
Down load service packs and software updates from an area with good unlimited Internet access to flash drives and use that to update machines on the sties with limited access.
Let the users at the site self police internet usage, once they understand that their Internet surfing impacts everyone else, they tend to self regulate each other.
I let the site management decide if they want better Internet access. Every time they've complained about the speed, I tell them the monthly cost to speed them up and they say the current access is just fine.
Use AV clients that use small update files instead of the multi megabyte files with each update.
Teach users not to send huge email attachments.
Be careful not to jump on the ASP band wagon when your infrastructure will not support the needs of externally hosted apps.
Dave