I managed to deploy several solution with conflicting features while developing. Now I can't access the admin central, is there a way to see all deployed solutions through stsadm?
you can use
stsadm -o enumsolutions
Be aware that its a best practice to always deploy from the same WFE. That way you wont have conflicts between hanging jobs. The problem is related to the fact that stsadm -o execadmsvcjobs only runs pending jobs on the WFE you are on, not on the entire farm. Gary Lapointe created a job that will run jobs on all servers: http://stsadm.blogspot.com/2008/10/better-execadmsvcjobs-stsadm-command.html
You can use SharePoint Manager to look at all the features which are installed and de-activate the ones causing conflict. This will at least get Central Admin back so you can perform some clean-up of the solutions from there.
SharePoint Manager is really useful for this kind of interaction with your environment: http://spm.codeplex.com/releases/view/22762