I don't know about you, but I often work in multiple Developer Edition (DE) instances of Force.com. I might be developing a customer prototype in one, using another for an upcoming webinar etc. It is therefore important for me to manage all the different DE Orgs efficiently. To that end, over time I have developed a small checklist of configuration changes that I make to each new DE Org that I sign-up for. I thought that this list might be helpful for some of the Force.com developers out there and so here goes.

1. Keeping track of my multiple logins across all the different DE Orgs is probably the most vexing problem for me. There are of course many different ways to address this issue. Having a consistent and easy-to-remember naming convention for all usernames/pwds, using OS/Browser specific tools like Trapdoor and 1Password for Macs and RoboForm for Windows to name a few. I have my own solution. I simply bookmark each new DE Org as such - https://login.salesforce.com/?un=<URL Encoded Username Name>&pw=<Password> – and label the bookmark appropriately (e.g 'Spring 11 Webinar'). That way, I don't have to remember my different logins and each login is only a click away.
2. Most of my development typically involves testing with multiple users (to test/simulate different User Roles/Profiles/Privileges etc). Once I create any additional test user and login in for the first time as that user, I make sure to 'Grant login access to your administrator' (Setup–>My Personal Information–>Grant Login Access). That way, I can easily switch between different users without having to login and logout every time and I don't have to remember yet another set of login credentials.
3. I enable 'Development Mode' for my user record (Setup–>My Personal Information–>Personal Information). This allows me to create and edit Visualforce pages via the browser.
4. When I'm developing in a DE Org, I don't like to get the daily Chatter email digests (or even Chatter email notifications). I typically disable all Chatter email in my DE org via Setup–>Personal Setup–>My Chatter Settings–>Chatter Email Settings. 
5. You might also want to add your corporate IP range to the Trusted IP Ranges for the Org (Setup–>Security Controls–>Network Access) to avoid getting activation link emails. If you plan on developing from outside your corporate firewall, you can also edit your User Profile (typically 'System Administrator') and set the Trusted IP Range to '0.0.0.0 – 255.255.255.255'. 
6. I set the User Password policy (Setup–>Security Controls–>Password Policies) to never expire. That saves me from having to think of new passwords every couple of months.

Please remember that the above tips are only applicable for a development/prototyping environment such as a DE Org. The security related configuration changes in particular (never expiring passwords, trusting all IP addresses etc.) should never be done in a Production Org since they violate security best practices and possibly your company's security policies. In addition, even if you only apply these tips to a DE Org, make sure that you don't store any sensitive data in that Org (which you shouldn't be doing anyway!).

Any other interesting DE Org tips and tricks you'd like to share with the community? Just comment on this post.