I've been working with DotNetNuke for over 7 years now and I find that following URL manipulation tips and tricks have saved me enormous amount of time. 

Changing the DotNetNuke Skin & Container 

Every now and then we find ourselves in the need to change the Skin/Container on a particular page but we do not have admin access to the site. Mostly this is when we're viewing our clients' sites and we want to rule out a CSS/JS conflict between our module and DNN Skin/Container. 

We can easily switch the DNN Skin by passing the ?SkinSrc=[G]Skins/_default/No+Skin parameter which is self explanatory: [G] points to the Portals/_default/ and the No+Skin is the name of the skin you want to override. Of course, the parameter should be URL Encoded. 

Similarly, we can override the container by passing the ?ContainerSrc=[G]Containers/_default/No+Container

Here are few ready to use URL Parameters that have been URL Encoded:

No Skin & Container
?SkinSrc=%5bG%5dSkins%2f_default%2fNo+Skin&ContainerSrc=%5bG%5dContainers%2f_default%2fNo+Container

Default DotNetNuke Skin & Container
DNN 5: 
?SkinSrc=%5bG%5dSkins%2fMinimalExtropy%2fIndex+1024&ContainerSrc=%5bG%5dContainers%2fMinimalExtropy%2fTitle_Blue

DNN 6: 
?SkinSrc=%5bG%5dSkins%2fDarkKnight%2fHome-Mega-Menu&ContainerSrc=%5bG%5dContainers%2fDarkKnight%2fPageTitle_Blue

View Specific Module Only

Sometimes we're only interested in viewing a single module on the page to rule out conflicts with other modules. This can be easily achieved by appending ?mid=xxx where xxx is the Module ID of the module.

Login & Register

It's often hard to locate login links on sites that are in their native languages other than English. Besides, sometimes we find skins with no login links at all. It's easy to login to any DNN site by simply appending ?ctl=login to the URL. Similarly, we can reach the registration page by appending ?ctl=register to any DotNetNuke URL. 

Show Specific DNN Module in iFrame

Using the tricks above, it becomes quite easy to show a specific DNN Module in an iFrame. We can use the ?mid=xxx parameter to target a single DNN Module and then override the Skin/Container if needed. This is great if you want to show a module from another site/page using an iFrame.