Cleon
Legend
I think Cleon's stat block is ridiculous boosterism. I can see bumping a hare's speed up to 40 feet, but a Con of 15? A Str approaching that of the average halfling? Sorry, but I refuse it.
As I keep arguing (see, chimpanzees), real-world animals are a lot more impressive than D&D gives them credit for. But boosting one animal without uptweaking all of the rest leads to imbalances and silliness.
That's all right demiurge, I'm not going to twist your arm and make you use those stats.

I think it's pretty good for something I threw together in a few minutes, it certainly looks more accurate than the Dragon 280 version.
I was aiming to stat up an unusually large and vigorous hare, i.e. a 9-12 pound Arctic Hare, since I thought that would make the most suitable hare-shape for a Small-sized supernatural familiar like a Tabur. For a more ordinary sized hare (~5 lbs) I'd drop the Con and Str by 2.
Since 9-12 lbs is halfway between Small and Tiny, I gave it a strength partway between. As for the halfling comparison, an average halfling weighs 30 pounds, so it's only a couple of times heavier than a large hare, and said hare should be proportionally stronger. The Constitution 15 was just to match a dog - a hare can usually outrun a dog, both by speed and stamina, so probably has a comparable Constitution. The SRD Dog is Small-sized and Con 15, and advancing between Tiny and Small does not give a Con change, ergo a hare should have a Con in that area.
As for the speed, a real life hare is as fast as a good horse (at least 30 mph, possibly up to 40-45 mph), and a fast horse in the SRD has 60 ft speed and the Run feat. I was strongly tempted to give hares a 50 ft. speed, the same as a Wolf, since a particularly fast dog (like a greyhound, which probably has speed of 50 or even 60 ft, with Run instead of Track as a bonus feat) has a good to excellent chance of catching a hare. Oh what the heck, I'll do it.
I do think I overrated the bite attack in my first draft, I'll cut it to 1d3 damage. I'm also tempted to add a couple of slam or unarmed strike attacks, so we can have "boxing hares".
So, putting that together I'd get a "Hares, mark 2" of:
Hare: CR 1/6; Tiny Animal; HD ½d8+1; hp 3; Init +4 (Dex); Spd 50 ft.; AC 16 (+2 size, +4 Dex); Atk bite –1 melee (1d3-3) or 2 unarmed strikes –1 melee (1d2-3 nonlethal); SQ scent; Face 2 1/2 ft. by 2 1/2 ft.; Reach 0 ft.; SV Fort +3, Ref +6, Will +1; Str 5, Dex 18, Con 13, Int 2, Wis 12, Cha 7. Skills: Hide +12, Jump +9, Listen +8, Spot +4, Feats: Alertness, Run (B).
Hare, Big: CR 1/4; Tiny Animal; HD ½d8+2; hp 4; Init +4 (Dex); Spd 50 ft.; AC 16 (+2 size, +4 Dex); Atk bite +0 melee (1d3-2) or 2 unarmed strikes +0 melee (1d2-2 nonlethal); SQ scent; Face 2 1/2 ft. by 2 1/2 ft.; Reach 0 ft.; SV Fort +4, Ref +6, Will +1; Str 7, Dex 18, Con 15, Int 2, Wis 12, Cha 7. Skills: Hide +12, Jump +10, Listen +8, Spot +4, Feats: Alertness, Run (B).
+4 racial bonus to Listen checks.
That looks pretty nice to me.Hare, Big: CR 1/4; Tiny Animal; HD ½d8+2; hp 4; Init +4 (Dex); Spd 50 ft.; AC 16 (+2 size, +4 Dex); Atk bite +0 melee (1d3-2) or 2 unarmed strikes +0 melee (1d2-2 nonlethal); SQ scent; Face 2 1/2 ft. by 2 1/2 ft.; Reach 0 ft.; SV Fort +4, Ref +6, Will +1; Str 7, Dex 18, Con 15, Int 2, Wis 12, Cha 7. Skills: Hide +12, Jump +10, Listen +8, Spot +4, Feats: Alertness, Run (B).
+4 racial bonus to Listen checks.
Besides, my feeling is that a lot of the problem comes from the 3E game system not handling particularly big or little creatures very well, but that's an argument for another day...