Text can be small
and readable. You can try looking for suitable pixel fonts that are made to be legible and compact.
Second, the remixSite logo is taking up a large portion of the real estate. There's no need for it to be that large; you could take out the circular graphic, which lets you bump the remixSite text further up and left. Now there's more space for the information below, so you can make the text larger. Think of more ways to compact the information; there's no need to insert the user's avatar in their sig (considering their postbits already have avatars!)
You can take a look at some examples of dynamically generated sigs:
See how small that "backloggery.com" text in the second sig is? You can also replace the "views", "downloads" and "ratings" labels with icons.