We use
DotProject. It’s not yet Web 2.0 but version 3 is based on the Zend framework and will be a complete reworking. Don’t know when it will be released though. Migration from version 2 is supported however. We’ve found it much more useful than
ProjectPier at this point. But preferences and needs vary.
Have also looked at
]project-open[ but you need some very specific requirements to self host, including PostgreSQL. Much of it is free and other elements not.
There’s also
TaskFreak for a very simple system.
In all cases, the challenge is usually getting your team to buy into using it. We’re fortunate enough to have some clients make all requests directly through DotProject (limiting their access to information only related to their business of course).