I don't really recall the details, just that there was a CharOps post at one time which delineated a Wizard with a +69 Arcana bonus. I'm guessing some of this might have been somewhat situational, like applying to checks when casting rituals, or at a restricted number of instances per day. It may have also assumed certain 'equivalencies', like rerolls being translated into the equivalent average bonus or something. I'm not sure, its been 10 years. @MwaO is the optimization guru...@AbdulAlhazred, @Ovinomancer
Here is the breakdown on Malstaph's Arcana skill:
+7 INT of 24
+6 Sage of Ages
+3 feat (Skill Focus)
+3 item (Ring of Wizardry)
+4 familiar (this is from a Book Imp familiar; +2 is a base feature of it, and the other +2 is because the familiar has the Eye of Vecna implanted in it)
The extra +2 in brackets applies to checks made in relation to rituals, and is the result of the Expert Ritualist feat.
In our game we use themes but not backgrounds (which can grant +2). If the character was a wizard rather than invoker as his main class we could expect +9 for INT of 28. That gets the bonus up towards +50. I don't think it's all that trivial to push it higher to +60 as a permanent feature.
I also recall some builds with VERY high Intimidation bonuses. This was a popular trick build, since you could get magic items that would impose bloodied, and then you could AP and force the monster to surrender without actually removing all its hit points, one of a VERY small number of ways to do that in 4e! (and the other ways were pretty much 'be an orbizard' which got nerfed a bunch).