I've found I don't have time to remain educated on everything that's out there, I don't have funds to invest in even a cross-section of the available materials, and I'm extremely unlikely to ever use most of what I already have, never mind anything new. As a result, I've basically stopped following new releases, except by a few key companies: WotC, Malhavoc and Green Ronin (also Mongoose's Babylon 5 line, and, recently, Paizo).
Of those companies I do follow, I at least look at everything, buy many of their products, and am generally satisfied with those things I do buy. There have been a few exceptions. I found Heroes of Battle, the Advanced Player's Manual and the Book of Roguish Luck to be disappointing, for example.
I also occasionally look into products I see recommended here, and sometimes something just catches my eye. However, it is fairly rare for me to stray from the main companies I follow.
As far as allowing things in my game is concerned, I find myself constrained by weight limits. I have to carry any books I'm using to my game (and I'm also the only member of my group to have a large library of books - three of four players in my last campaign didn't even have the PHB v3.5!). Since I can only carry so much, I've taken to allowing Core Rules only. Since I now have to move for work reasons, I'm hoping to find a new group, and may find that circumstances change if, for instance, I can drive to the game. My preference would be to allow a handful of carefully chosen supplements, depending on the campaign, on an almost book-by-book basis.
As regards whether the OGL has helped Wizards, I think it definately has. If nothing else, the proliferation of d20 materials has led to a lot of game stores increasing the shelf space for D&D and d20, at the expense of every other system, which means new players are almost certain to come in via d20. The wide variety of materials has kept the game fresh, which probably aids with customer retention (rather than leave D&D behind, they pick up a 3rd-party supplement this month, and maybe get the WotC book next month). The fact that Necromancer and Goodman (amongst others) are producing adventures spares Wizards the burden of producing their own, at a margin that probably isn't sufficient for them.
So, yes, I think the OGL has definately helped Wizards. However, I think they could do more to improve the extent to which the OGL is helping them:
I think Wizards are doing themselves a disservice by not releasing the vast majority (if not all) of new monsters, spells and feats as OGC. This means that that material cannot be reused and expanded on by the 3rd party producers. So, if you find a really cool monster in the Fiend Folio, the only place where you might find an ecology is Dragon magazine. The only place where you'll see it in an adventure is Dungeon magazine (and perhaps Kenzer's products - I don't know how that license works). The monster will never feature in the background of any new setting (no ancient Spellweaver empires in Midnight, or Oathbound, or...). Granted, a 3rd-party producer could approach Wizards to ask for permission, but that requires effort on their part, and on Wizards' unless their answer to all such requests is a blanket "no". And effort, in this instance, costs money. So, better to just do something else. Create your own powerful race of mysterious spellcasters. Which means that the IP value of the Spellweaver does not increase from this new use.
(My justification for the last statement: Beholders are particularly valuable because they are identified as one of the iconic monsters of D&D. Why are they so identified? Because they were widely used as a D&D monster. Likewise, the only place you'll see Spellweavers is in a D&D game - as far as I know - but unless they're widely used, they remain a little-known creature. In this instance, more use for such a creature would make it more familiar to D&D players as an iconic monster, and thus make the creature more valuable. If nothing else, it then allows WotC to produce a "Lords of Madness II" featuring the new monsters that have become iconic through use. My use of Spellweavers in the previous example is, of course, entirely arbitrary. I just happen to like them.)