In Shrinking SQL Server 2005 log files I gave some standard approaches to shrinking transaction logs. I was having trouble making those work on a development server, due in part to an extreme shortage of disk space. I came up with a neat little trick that seems to work pretty well, with some caveats.
The trick is to change the database recovery model from Full to Simple, change the recovery model back to Full, then do the dbcc shrinkfile. (The recovery model is found in the database’s properties in SQL Server Management Studio.) I think this works because changing the model to simple clears the committed transaction log entries, effectively emptying the transaction log if it is not actively being used (in which case this is probably not a good idea anyway). I should note that in case Something Bad Happens™, it would be prudent to take a backup of the database first if possible.
Hopefully the combination of the previous article and this little trick will help you get those transactions logs back under control.