If there's commonly used data that would be good for indexing or filtering, you can take a few key values and keep them stored in their own fields.

There are also often functions that can parse structured text like XML or JSON so you can store data in blobs but not actually need to query all the blobs out to a client to use them on the database side and retrieve specific values. Another nice thing about blobs is the data can be somewhat flexible in structure. If i need to add a field to something that is a key/value pair inside a blob, i dont necessarily have to change a bunch of table schemas to get the functionality on the front end that I'm after. Just add a few keys inside the blob.