Mr Bluesky, luckily there are loads of decent knives in the 3" blade length range. In fact, some companies offer a couple of models with blades just a hair under 3" to be on the safe side when it comes to legal limits.
Although there are no legal blade length limits where I live, a 3" blade is still my favourite for urban EDC. So here are a few I like and have worked well for me. Other than the info on materials, the rest is highly subjective and just my opinion as a user.
-Spyderco Delica 4. If I had to keep a single folding knife for everyday urban use, it would probably be one of my Delicas. Sure, they aren't going to win any beauty pageants, but the design just works.
There are several versions out there, in different colours and edges (plain, fully serrated or combo). You can also get one with an Emerson wave opening feature, and there are blunt trainers available (both with and without the wave opener). Most of them have a sabre grind that works well because of the blade thickness and very good FRN handles, but you can still find some of the discontinued flat ground model with foliage green G-10 handles. The G-10 model is heavier than the regular FRN models, but I like it a lot. There's a new variant coming out soon, a flat ground blade with FRN handles (a few different colours will be available) that should combine the best of both previous models.
I don't think a regular Delica 4 will let you down. You get a lot of knife for your money. The blade steel is excellent (VG-10), the handle is very comfortable and secure (it's got a nice texture), you can place the clip in four different positions and it only weighs 2.6oz!
Blade length is 2 7/8". Costs around $50.
Spyderco Delica 4, FRN Handle, Plain Edge
-Spyderco Caly3. I'm a huge Spyderco fan, they offer really great knives and even better customer service, so they get a lot of my business. Many people consider the Caly3 the
3" EDC production folder. For it's size, it's really heavy duty. Full steel construction with G-10 handle slabs and a fantastic full flat ground blade made out of VG-10.
It comes with a deep carry wire clip that makes it very discreet. The handle is really well thought out for utility tasks, but if you've got large hands and SD is part of your reason for carrying a knife, try to handle one before buying. I've got big hands and find the slightly larger handle on the Delica better for SD training.
There's a more upscale model with a laminated ZDP-189 blade and carbon fibre handle slabs, but I don't think the price difference is worth it. The regular model costs around $100 (and you can get it plain or serrated).
Spyderco Caly 3, G-10 Handle, Plain Edge
-Benchmade Mini-Griptilian. Another excellent light weight EDC knife. I've got a couple of full size models as well as some minis and they are great. You can choose from several different blade shapes, edge types, handle colours and steels. Pick the one you like the most. My favourites are the ones with a modified sheepfoot blade and plain edge in 154CM steel (I just prefer the opening hole to a thumbstud and find the blade design really practical).
The AXIS lock used on these knives is great, very smooth and secure. The handle is also really comfortable. It's thicker than the handle on the Delica, some people don't like that. I'm quite fond of it, the small extra pocket space is well worth the excellent ergonomics.
Benchmade Mini Griptilian, Black Noryl GTX Handle, Plain Edge
-Kershaw Leek. This is a great EDC knife! A very light and slim Ken Onion design with fantastic blade geometry and assisted opening (you can easily turn it into a manual only folder if you need to).
There are a lot of different models out there, my favourite is the one with G-10 handles and S30V blade. The ones with the metal handle are fine for utility use, but for emergency SD use the grippy G-10 is much better. Combine that with an excellent steel like S30V all for less than $80 and you've got a great EDC knife. Some of the other versions are cheaper, like the great 13C26/CPM-D2 composite blade Leek which I love to death (costs $50!).
Kershaw Ken Onion Leek, G-10 Handle, S30V Stone Washed Blade, Plain Edge
-Lonewolf Blackfoot. I ordered this one by mistake, I wish I made more mistakes like this one! I think it's a great value for the quality and materials you get. S30V blade, G-10 handle (there's a variation with ebony inlays). It's rather hefty for its size at almost 5oz, but you get a very strong knife built like a tank.
I don't know if it comes with a satin finished blade (I'm not a huge fan of coated blades). I'm really happy with mine, so much so that I ordered the Longhorn (its bigger brother). Price is around $80.
LoneWolf Blackfoot, G-10, Plain Edge
Those are just a few I think could work for you. I only included the knifeworks.com links for reference and because they've always given me great service.