I don't know what it is called today, but I have had for years a tool called a bodkin. It is metal with a small ball on one end and an eyelet on the other end. The ball end is used to turn corners, and the other end helps guide elastic or ribbon thru a casing. In my day every self-respecting seamstress had one. I think they still make them. They are inexpensive and should be at a good notions store.
Happy quilting
Severna

and the milk jug thing is wonderful for creasing a seam or Scrap booking LOL

have you checked on Clotilde.com that site has lots of different tools, just do a search when u go to her site

It is an orange wood cuticle stick. I have one on my sewing table all the time, pointy on one end and flat on the other. You can buy them at any Walgreen's, but be sure to get the good one. Edie

I would give you a little of my brain but it's almost gone too....LOL (wait..it's not a lauhing matter)

Oh yeah I have one of those from years ago!

I found a plastic one at WalMart in scrapbooking area: a Martha Stewart paper creaser.

Try the end of a paint brush. You know, one of those paint by number ones.

Try folding the fabric into the seam instead of poking it in. Fold along the seam line on one side of the corner. Then fold the other, again on the seam line and the corner will lie flat upon the other folded side. Put the folded corner between your fingers and turn the corner onto itself. This should make those seams lie flat when turned right side out. If you are just poking those seams into the corner, you will end up with a fat corner. I use this method and then a heavy pointed needle or a dull machine needle (that's what those are for!) to sort of pull that out then from the outside to create a really sharp corner. Works for me anyhow.

How about a thingey! LOL!