Constitution items

[Half-orc Bard]

Are there any items that boost constitution besides the amulet

[Hirax]

Check out pages 233 and 234 of the magic item compendium.

[ericgrau]

The ioun stone, belt of magnificence (MiC, I think that's what it's called), and Magic Item Compendium (MiC) alternate rules allowing ability score bonuses on existing items.

[Keld Denar]

Belt of Dwarven Dwarfiness gives you a +2 enhancement bonus to Con, as well as diplomancy bonuses vs people with beards.

[Aemoh87]

Even better question, are there any items that boost con that is not an enhancement bonus.

[ffone]

There are the Manuals / Tomes for inherent bonuses, up to +5...rather expensive, and the sort of thing that's 'always worth it eventually' for high level rich chars.