Don't delete anything in your blobs folder. Those are your nandroid backups. Starting with CWM6, it makes incremental backups and your backup files point to the files in the blobs folder. To free up space, delete unwanted backups and the next time you run a nandroid it will delete the unneeded files in the blobs folder.
I can confirm that deleting the contents of the 'blobs' directory does no harm whatsoever. This ASSUMES that you're also deleting the contents of the 'backup' directory, which is what I did.
I had a VERY stable ROM/Kernel/Gapps build on my Sprint Galaxy Nexus and nearly 20 GBs of backups. All I wanted to do is delete everything, backup that stable build, and then get ready for the next set of ROMs and Kernels coming down the pike.
After deleting everything and completing a fresh nandroid backup, I went back in and verified that the 'blobs' folder was indeed repopulated with a fresh set of incremental backup files (roughly 3000+ folders). After Google restored all my apps, I now have roughly 23 GBs of free space. It rarely gets any better than that.
So, it's completely safe to delete everything (backups AND blobs) and start over with a fresh backup. Apparently that portion of CWM (version 6.0.1.0) is very forgiving and doesn't care if you delete the contents of those two directories. Good code.
Just an FYI --- I use a very handy Windows based (there are also other OS variants) program called 'Android Commander' to copy, delete and move files around on my Nexus. It is very similar to 'Total Commander', if you're at all familiar with that application. Google it if you don't already know about it. Good stuff.
AL