If you can find them at a brick and mortar store, that is.
Cricket with a 1 7/8" blade of ATS 55. I have one and it is a great little utility blade for small jobs such as picking splinters out of a finger.
D'Alton Holder Toad with a 1 7/16" blade. This is an expensive, relatively, little dude, but many people swear by them.
Navigator is a long-time Spydie favorite. It comes with a 2 1/8" VG-10 blade and gun-metal blue Almite scales. It is quite handsome and very useful. It fits my hand very well, indeed, and I would carry it but for my love for the Li'l Temperance.
Meerkat is the knife I got just after 9/11, when it was not a good idea to attract too much attention to oneself by carrying something like a Gunting, which had been my EDC up until then. It's blade is 1 15/16" of either 440C or AUS6 steel in one of two shapes, spear point or reverse "S", like the Cricket. It has the trickest lock out there and its clip is all but invisible. When clipped into a pocket, it is definitely a "low-observable" item. I like it very much when I am going places where I wish not to be noticeable with my knife.
Jester is available with a 1 15/16" modified spear point blade of AUS6 steel and is very inexpensive. I have no experience of this knife.
The Ladybug is an even less expensive old classic of Spyderco's. It, too, has a 1 15/16" blade of AUS6, but its blade is rather more pointed than that on the Jester. It has been successfully used for self-defense on a number of occasions, or so the posts have read.
A very hot new item just out is the Salsa. It has all of the bits to make it a very good self-defense knife in the under 2.5" class. It has a 2 7/16" blade, a "Cobra Hood" over the Spydie hole making it easier to open, so they say, and a Compression Lock nested in aluminum scales. The Compression Lock is probably one of the, if not the, best blade locking systems available today. I have them on a number of my knives, including my Lil Temperance, and I swear by them. I have not personally tried a Salsa, although I do intend to do so shortly.
Now, if you are considering carrying a second knife just for self-defense, which is what Sal Glesser and others recommend that you should do, then you might wish to consider the Salsa for that and one of the others or the following for your utility choice. This knife is a bit of an odd one, even for Spyderco, but I have one of their original versions and I really like it for a sort of general purpose carry. It is the Mini-Dyad or Dyad Junior, whatever it is currently called. This is a small knife with two blades, each 0f 2 1/4", one plain edged and the other with Spyder teeth, so that you have both available should you need one or the other. It uses a simple lock back system for both blades and, in its current form, has FRN scales and no clip, so that it simply drops into your pocket.
There you have what I think to be the most up-to-date list of Spyderco's little knives, and a short commentary on each. I hope that you do find it helpful. As to the need for a knife that you carry specifically for self defense, I can only refer you to the Spyderco Forum and to Sal's many, many comments to that effect. Perhaps the more self-defense oriented might wish to expand upon this.