If you are interested in a powerful, versatile and flavorful build, try this:
Races
Arcane Gnome [Dragon 291]
Whisper Gnome [RoS 96]
Prestige Classes
Shadowcrafter [Und 43]: 8-10 levels
Shadowcraft Mage [RoS 121]: 5 levels
Shadow Adept [PGtF 72]: 1 level
Feats
1: Spell Focus (Illusion) [PHB 100]
3: Shadow Weave Magic [PGtF 43]: +1 DC & SR checks for illusion, enchantment, necromancy
5: Heighten Spell [PHB 95]
6: Greater Spell Focus (Illusion) [PHB 94]
9: Earth Sense [RoS 138]
12: Earth Spell [RoS 138]
15: Enhanced Shadow Reality [Dragon 325]
18: Easy Metamagic (Heighten) [Dragon 325]
Alternate: Tattoo Focus [DMG 194]: +1 DC and caster level to specialized school
Free: Scribe Scroll, Alertness
Variants from Unearthed Arcana
Illusion Domain (I prefer to create a custom Shadow Domain) [UA 56]
Illusion Specialist Substitution [UA 63]
1) Chains of Disbelief
1) Shadow Shaper – You’ll only get the 1st and 5th level abilities, but Hide as a class skill and adding Intelligence modifier to Hide checks is great.
1) Illusion Mastery
Gnome Illusionist Substitution [RoS 149]
1) Gnome Illusionist Spells – I like having silent image at 1 level lower. It makes the heightened Silent Images just that much better. I’d probably choose {Abjuration, Divination, Enchantment, Necromancy, Transmutation} to be cast 1 level lower.
5) Extended Illusions – I’d rather have the bonus feat and the two spells learned at that level, especially since the Shadowcraft Mage doubles the duration already
10) Insidious Illusions – Probably won’t make it to 10th level wizard, otherwise it is pretty cool, but similar to the insidious ?? gained by the shadow adept
Become a wizard specializing in illusions. Make liberal use of Heightend Silent Images which are transformed by your feats and class abilities into (shaodow) spells which can mimic the effects of Shadow Conjuration and Evocation. You will have no problem with SR due to the Earth Spell feat, and you can mimic tons of spells.
Here is a formula I use for figuring out how effective my heightened Silent Images are:
Heightened illusion (shadow) spells are x% real, where x = lvl*10% + { +20% Enhanced Shadow Reality, +20% Powerful Shadow Magic, +10%-20% for conjurations and evocations, +10% if standing on earth/stone }
Have fun!