While building a character for an Evil campaign, and at the same time one I'll go and use in a real campaign as a BBEG if I get the chance, I started wondering:

Are there (m)Any anti-construct spells?

Depends on your construct. Rusting Grasp is a good bet.

Damage spells from Eberron
Deconstruct kinda like harm for constructs.
rusting grasp if they are made of metal.
actually look in the eberron setting for alot of construct based spells

Grease is a good anti-golem spell. They have lousy Dex scores and no ranks in Balance (or anything for that matter) so they have serious issues.

Stone to Mud for stone golems

It states in many golem entries what spells can hinder/help them. I'm pretty sure the spell compendium has some construct spells.

Any spell that does not have spell resistance, works. It states in the MM that Golem's are immune to any spell that allows for Spell Resistance (unless noted otherwise). Creativity is a must for a spell caster going up against one.

In general, Conjuration school spells are rarely subject to spell resistance, and thus useful against golems and other constructs that have spell immunity or the like--so spells like grease, acid fog, Melf's acid arrow, and sleet storm can usually hamper constructs or even damage them. Other spells that can be used to attack indirectly are also quite handy. Transmute rock to mud followed by its inverse, for example, can be quite effective against any golem if it is on (or under) a natural stone surface. Objects hurled by telekinesis, buff spells that make your allies less vulnerable to the construct's attacks or grant their weapons the qualities needed to attack effectively, summoned monsters to absorb attacks and/or flank the construct--all of these are useful things for a caster to do in such a battle. Things to control the battlefield can also be handy--web, some of the various wall spells, Evard's black tentacles, etc.--can also be helpful, although larger constructs generally have the size and strength to make such barriers less effective than they are against medium-sized creatures.

My personal favorite is summoning lantern archons by the barrel and leaving them to do their thing. Their attack bonus isn't very high, but they're touch attacks that ignore all DR and SR, and golems tend to have single digit touch ACs, so you can whittle 'em away easy enough.

Good tactic if you can get out of the way while they chip away at the golem's health.