Can Haste allow me to cast two spells (not quickened) in one round? This is given that haste gives an extra attack on a full round action, if I take a full round action can I cast two spells?
Only If Using Haste from Dungeons and Dragons, 3rd Edition
The Player's Handbook (2000) for Dungeons and Dragons, 3rd Edition has on page 212-3 the spell haste, which reads
The Player's Handbook (2000) explains that
This unhelpful description is followed a few pages later by Table 8-3: Partial Actions, which among other available options is cast a spell (but not spells with long casting times) (PH 127).
This didn't go unnoticed by Dungeons and Dragons, 3rd Edition players for long. By Defenders of the Faith (May 2001), the necessity of haste was so severe that the following armor special ability was published therein:
This is an ability that all but the newest contemporary Dungeons and Dragons 3.5 player recognizes as ridiculously powerful, but at the time it wasn't overpowered, and instead an effort to equalize the haves (wizards et al.) and have-nots (everyone except wizards et al.).
This was changed by the Dungeons and Dragons 3.5 revision, but--for a few years, anyway--the spell haste did, indeed, allow the casting of multiple spells per turn.
No. Casting a spell is usually a standard action, though some are cast as Move, Swift, or Immediate instead. The effect of Haste reads "When making a full attack action, a hasted creature may make one extra attack with any weapon he is holding." It states specifically that it only has an effect when making a full attack action, and the effect it has is that it grants one extra attack (it goes on further to note that it doesn't stack with the Speed enchantment and such, but that's not relevant to your question.)
In short, because the Haste spell doesn't grant you extra standard, move, or swift actions and because it doesn't specifically say it allows you to cast extra spells, using Haste doesn't allow you to cast more spells in a given round than you otherwise would.
No: from the on-line SRD
This was the case from OD&D through to at least early 3.5e, with the exception of D&D 3e.
If I can venture an opinion, because of the way Vancian magic works this is a little like asking whether you can ask me to drive to your house twice as quickly because you have haste cast on you. Magic is like electricity and flows through the "circuit" created by your verbal, somatic, and material components at a set rate determined by those components, not the speed at which you perform them; and in fact hurrying them will prevent the spell working at all (if you're lucky and the DM doesn't roll for a chance that the spell will backfire :) ).