What do you guys think of this suggestion?

I'd been thinking of doing this for my own installation, so yes, good idea.

I do think they should be per-project profiles though. Users should still be able to set their own profiles, or use a predefined one and modify it. However, for some projects you may want to have only a default profile to be used by everyoe (e.g. when you have a project for your own Mantis installation, there can be only one profile, really).

Um, but the profile can reflect what client the user is on, or whether the install is on a local/development server vs. the release server. I have bugs that show up on Mozilla 1.3, but not 1.2b. I have bugs that show up on FreeBSD / release server, but not on the WinXP machine I start with.

Maybe server-defined profiles would be ok, if user could sub-class them? Or if they were offered in addition to user profiles?

It depends entirely on what kinds of "products" you use the bug tracker for. If it's a poduct that can be downloaded and installed on a client machine, then yes, you'd want to know what the the user's environment is. If it's a product that is installed on a (single) web server, then the profile would be basically teh platform that webserver uses - though (depending on the product/service) you might want to know what user agent the user is using. And if it's a service installed on a server in an intranet, there's probably no variation at all, and you wouldn't want to be confused by users posting with different profiles.

In other words, there should be an option on a per-project basis to either let users define their own profiles, or have a fixed profile which would be the same for every user in that project. More configurability might be useful, too - especially for web-based products, where you'd want to know about user agents in addition to the fields provided now. Maybe the latter could be solved with custom fields, though, but it would still need to be tied to a project.

I have committed basic support for global profiles. This can be expanded to per-project profiles later.