MarkB said:What exactly do you want out of you arcane rogue, in terms of both roguely things and spellcasting? Rather than a PrC, you might want to try the Beguiler. It gets all the rogue skills, but lacks some of their class features such as sneak attack and evasion, though its own class features are oriented towards a rogue-type role. Even if you want the basic rogue features, you may find it better to multiclass with beguiler than with some of the spellcasting PrCs.
Mistwell said:"I love how the Spellthief is set up for this but I don't want the class abilities." Looked pretty clear to me that he already considered and rejected this idea.
Mistwell said:Here is the list of Arcane Rogues from the 3.5 Rogue Optimization thread over at WOTC:
http://boards1.wizards.com/showthread.php?t=132214
arcane rogues
- rogue1/wizard5/guild thief1/arcane trickster10/guid thief3, by nikademus
-Rogue 3/Sorceror 6/Arcane Trickster 10/? 1 by Ranthanas
-Rogue 3/Sorceror 4/Virtuoso 3/Arcane Trickster 10 by Ranthanas
-Rogue 3/Sorceror 4/Virtuoso 9/Arcane Trickster 4 by Ranthanas
-Rogue 3/Sorceror 2/Spellsinger 5/Arcane Trickster10 by Ranthanas
Rogue 4/Barbarian 1/Assassin 8/Nar Demonbinder 1/Arcane Trickster 6 by Rathanas
If you are going outside of WOTC sources, I think the Mage Blade from Monte Cook's Arcana Evolved might be what you are looking for.
Duskblade is a bit rogue-like (from PHB II).

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.