A while ago, I started trying to figure out how to combine dervish and tempest without losing (too much) BAB, among other things.
Then I noticed that according to our campaign's newly redesigned house rules, grey elves (the more gregarious and art-focused subrace of our campaign's elves) always get Perform as a class skill.
I used ranger 2 for the skill points, in particular to meet the Perform prerequisite of dervish (not to mention Two-Weapon Fighting for tempest). Barbarian 1 get a +10 ft. speed bonus, which helps a dervish's dance. (And they can rage as a back up ability.) Fighter 2 makes it pretty easy to quickly pick up the required feats.
Dervish 3 gets Spring Attack as a bonus feat, which helps to meet the tempest requirement.
I plan on maxing out Balance, Jump, Tumble, and Perform (dance), and putting all attribute enhancement in Dexterity.
1st Ranger 1 Dodge
2nd Fighter 1 Weapon Focus (scimitar)
3rd Barbarian 1 Mobility
4th Ranger 2
5th Fighter 2 Combat Expertise
6th Dervish 1 Improved Two-Weapon Fighting
7th Dervish 2
8th Dervish 3
9th Dervish 4 Weapon Finesse
10th Tempest 1
11th Tempest 2
12th Tempest 3 Improved Critical (scimitar)
13th Dervish 5
14th Dervish 6
15th Dervish 7 Two-Weapon Defense
16th Tempest 4
17th Tempest 5
18th Dervish 8 Greater Two-Weapon Fighting
19th Dervish 9
20th Dervish 10
The reason I alternated dervish and tempest is that they get certain critical abilities at certain levels, and I wanted my PC to take advantage of these as early as possible.
I think there are better combos for dervish (for example, using the thief-acrobat prestige class), but I really wanted a PC very focused on fighting. If I'm missing anything obvious here or have made a mistake in the build, go ahead and point it out, that's why I'm posting it here.